Murder mystery sudoku — the daily cases for 12 September 2026

Every detective in the world got these same crime scenes on 2026-09-12 — each difficulty published twice, once untimed and once as time attack. Each case is procedurally generated and then proved to have exactly one logical solution before it is published, including the cases where somebody is lying. You place every suspect back on the map using only their testimony: exactly one person per row, never two in a column. Whoever is left alone with the victim did it.

Beginner — The Old Observatory

A 5×5 grid across 3 rooms: Lounge, Office, Cellar. Seven statements, seven squares nobody could stand on, and enough testimony that the surplus is what pins the last two down.

Cracked by 13 detectives so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

The testimony

What each person said, and how much of the board it rules out.

Hilda was in the leftmost column. leaves 4 of 21 squares
Show it on the board
The squares this one statement leaves Hilda: 4 of 21.
Hilda was in row 2. leaves 1 of 21 squares
Show it on the board
The squares this one statement leaves Hilda: 1 of 21.
Ines was in the lounge. leaves 10 of 21 squares
Ines was in the top row. leaves 2 of 21 squares
Show it on the board
The squares this one statement leaves Ines: 2 of 21.
Marco was in the cellar. leaves 8 of 21 squares
Show it on the board
The squares this one statement leaves Marco: 8 of 21.
Marco was in column 4. leaves 1 of 21 squares
Show it on the board
The squares this one statement leaves Marco: 1 of 21.
Nico was in the cellar. leaves 8 of 21 squares
Show it on the board
The squares this one statement leaves Nico: 8 of 21.

Show the squares Ines had left

The squares still open to Ines once their own statements are taken into account — 2 of 21.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Ines can only be in Lounge (row 1, column 5) — down from 2 possible squares.
Nico can only be in Cellar (row 4, column 2) — down from 8 possible squares.
Lorenzo can only be in Lounge (row 3, column 3) — down from 21 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Ines, in Lounge (row 1, column 5).

Show the solved board

The only arrangement the testimony allows. Ines is ringed in red.

Beginner · time attack — The Old Observatory

A 5×5 grid across 4 rooms: Archive, Office, Cellar, Workshop. Seven statements, six squares nobody could stand on, and enough testimony that the surplus is what pins the last two down.

Cracked by one detective so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

The testimony

What each person said, and how much of the board it rules out.

Frida was in column 4. leaves 3 of 22 squares
Show it on the board
The squares this one statement leaves Frida: 3 of 22.
Frida was in the top row. leaves 1 of 22 squares
Show it on the board
The squares this one statement leaves Frida: 1 of 22.
Dora was in the bottom row. leaves 4 of 22 squares
Show it on the board
The squares this one statement leaves Dora: 4 of 22.
Dora was in the cellar. leaves 3 of 22 squares
Show it on the board
The squares this one statement leaves Dora: 3 of 22.
Paloma was in the archive. leaves 4 of 22 squares
Show it on the board
The squares this one statement leaves Paloma: 4 of 22.
Marina was in column 2. leaves 4 of 22 squares
Show it on the board
The squares this one statement leaves Marina: 4 of 22.
Marina was in the workshop. leaves 1 of 22 squares

Show the squares Dora had left

The squares still open to Dora once their own statements are taken into account — 3 of 22.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Dora can only be in Cellar (row 5, column 3) — down from 3 possible squares.
Paloma can only be in Archive (row 2, column 5) — down from 4 possible squares.
Bianca can only be in Cellar (row 3, column 1) — down from 22 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Dora, in Cellar (row 5, column 3).

Show the solved board

The only arrangement the testimony allows. Dora is ringed in red.

Easy — The Old Observatory

A 6×6 grid across 5 rooms: Lounge, Workshop, Cellar, Garden, Terrace. Six statements, eight squares nobody could stand on, and no assumption anywhere: elimination alone closes it.

Cracked by 11 detectives so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. A — armchair (square stays free) · CH — chest · CR — crate · F — flower bush · G — grandfather clock · TE — telescope · TR — tree · W — window (square stays free)

The testimony

What each person said, and how much of the board it rules out.

Quentin was beside the crate. leaves 1 of 30 squares
Show it on the board
The squares this one statement leaves Quentin: 1 of 30.
Hilda was beside the grandfather clock. leaves 2 of 30 squares
Show it on the board
The squares this one statement leaves Hilda: 2 of 30.
Kaspar was seated on the armchair. leaves 1 of 30 squares
Show it on the board
The squares this one statement leaves Kaspar: 1 of 30.
Petra was in row 2. leaves 5 of 30 squares
Show it on the board
The squares this one statement leaves Petra: 5 of 30.
Petra was in the garden. leaves 2 of 30 squares
Show it on the board
The squares this one statement leaves Petra: 2 of 30.
Walter was beside the flower bush. leaves 2 of 30 squares
Show it on the board
The squares this one statement leaves Walter: 2 of 30.

Show the squares Hilda had left

The squares still open to Hilda once their own statements are taken into account — 2 of 30.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Hilda can only be in Workshop (row 5, column 1) — down from 2 possible squares.
Elena can only be in Garden (row 1, column 4) — down from 30 possible squares.
Petra can only be in Garden (row 2, column 6) — down from 2 possible squares.
Walter can only be in Terrace (row 4, column 5) — down from 2 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Petra, in Garden (row 2, column 6).

Show the solved board

The only arrangement the testimony allows. Petra is ringed in red.

Easy · time attack — The Old Observatory

A 6×6 grid across 5 rooms: Office, Archive, Terrace, Library, Garden. Eight statements, ten squares nobody could stand on, and no assumption anywhere: elimination alone closes it.

Cracked by one detective so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. A — armchair (square stays free) · B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · FL — floor lamp · FO — flower bush · W — window (square stays free)

The testimony

What each person said, and how much of the board it rules out.

Felix was in row 2. leaves 5 of 29 squares
Show it on the board
The squares this one statement leaves Felix: 5 of 29.
Felix was in the library. leaves 2 of 29 squares
Show it on the board
The squares this one statement leaves Felix: 2 of 29.
Selma was in row 3. leaves 5 of 29 squares
Show it on the board
The squares this one statement leaves Selma: 5 of 29.
Selma was in the terrace. leaves 2 of 29 squares
Show it on the board
The squares this one statement leaves Selma: 2 of 29.
Oscar was in the garden. leaves 6 of 29 squares
Show it on the board
The squares this one statement leaves Oscar: 6 of 29.
Delia was beside the window. leaves 1 of 29 squares
Show it on the board
The squares this one statement leaves Delia: 1 of 29.
Marina was in the office. leaves 5 of 29 squares
Marina was in column 2. leaves 1 of 29 squares

Show the squares Felix had left

The squares still open to Felix once their own statements are taken into account — 2 of 29.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Felix can only be in Library (row 2, column 4) — down from 2 possible squares.
Selma can only be in Terrace (row 3, column 5) — down from 2 possible squares.
Oscar can only be in Garden (row 5, column 1) — down from 6 possible squares.
Horacio can only be in Library (row 4, column 3) — down from 29 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Felix, in Library (row 2, column 4).

Show the solved board

The only arrangement the testimony allows. Felix is ringed in red.

Medium · time attack — The Old Observatory

A 7×7 grid across 6 rooms: Library, Garden, Terrace, Cellar, Lounge, Workshop. Eight statements, twelve squares nobody could stand on, almost as many rooms as suspects, so a room claim nearly names a square, and no assumption anywhere: elimination alone closes it.

Cracked by one detective so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · F — flower bush · P — potted plant · SO — sofa (square stays free) · ST — statue · T — tree · W — window (square stays free)

The testimony

What each person said, and how much of the board it rules out.

Wilfred was in the same row as the tree. leaves 4 of 40 squares
Show it on the board
The squares this one statement leaves Wilfred: 4 of 40.
Wilfred was beside the sofa. leaves 1 of 40 squares
Show it on the board
The squares this one statement leaves Wilfred: 1 of 40.
Zaida was in the same column as the desk. leaves 5 of 40 squares
Show it on the board
The squares this one statement leaves Zaida: 5 of 40.
Vivienne was in the garden or in the cellar. leaves 8 of 40 squares
Show it on the board
The squares this one statement leaves Vivienne: 8 of 40.
Dante was in column 6. leaves 5 of 40 squares
Show it on the board
The squares this one statement leaves Dante: 5 of 40.
Dante was on the carpet. leaves 1 of 40 squares
Show it on the board
The squares this one statement leaves Dante: 1 of 40.
Celeste was beside the potted plant. leaves 2 of 40 squares
Nestor was in the same row as the crate. leaves 5 of 40 squares

Show the squares Celeste had left

The squares still open to Celeste once their own statements are taken into account — 2 of 40.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Zaida can only be in Lounge (row 2, column 2) — down from 5 possible squares.
Vivienne can only be in Garden (row 5, column 3) — down from 8 possible squares.
Irene can only be in Terrace (row 4, column 5) — down from 40 possible squares.
Celeste can only be in Terrace (row 1, column 7) — down from 2 possible squares.
Nestor can only be in Lounge (row 3, column 1) — down from 5 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Celeste, in Terrace (row 1, column 7).

Show the solved board

The only arrangement the testimony allows. Celeste is ringed in red.

Medium — The Old Observatory

A 7×7 grid across 6 rooms: Office, Dome, Library, Garden, Cellar, Archive. Eight statements, thirteen squares nobody could stand on, almost as many rooms as suspects, so a room claim nearly names a square, and no assumption anywhere: elimination alone closes it.

Cracked by 12 detectives so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · FL — floor lamp · FO — flower bush · G — grandfather clock · SO — sofa (square stays free) · ST — statue · TE — telescope · TR — tree · W — window (square stays free)

The testimony

What each person said, and how much of the board it rules out.

Olivia was seated on the sofa. leaves 2 of 39 squares
Show it on the board
The squares this one statement leaves Olivia: 2 of 39.
Vasco was in the same room as the Magician.
Vasco was beside the bookshelf. leaves 4 of 39 squares
Show it on the board
The squares this one statement leaves Vasco: 4 of 39.
Milo was in the same room as the Magician.
Milo was in the same row as the statue. leaves 4 of 39 squares
Show it on the board
The squares this one statement leaves Milo: 4 of 39.
Ignacio was beside the floor lamp. leaves 1 of 39 squares
Show it on the board
The squares this one statement leaves Ignacio: 1 of 39.
Felix was in the same row as the window. leaves 11 of 39 squares
Show it on the board
The squares this one statement leaves Felix: 11 of 39.
Zeno was somewhere south of the Curator.

Show the squares Olivia had left

The squares still open to Olivia once their own statements are taken into account — 2 of 39.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Tristan can only be in Archive (row 1, column 6) — down from 39 possible squares.
Olivia can only be in Dome (row 7, column 4) — down from 2 possible squares.
Vasco can only be in Cellar (row 6, column 3) — down from 4 possible squares.
Milo can only be in Cellar (row 5, column 2) — down from 4 possible squares.
Felix can only be in Archive (row 2, column 7) — down from 11 possible squares.
Zeno can only be in Cellar (row 3, column 5) — down from 39 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Felix, in Archive (row 2, column 7).

Show the solved board

The only arrangement the testimony allows. Felix is ringed in red.

Hard — The Old Observatory

An 8×8 grid across 6 rooms: Archive, Terrace, Dome, Office, Lounge, Workshop. Fourteen statements, sixteen squares nobody could stand on, and one round of assume-and-test after elimination ran dry — and one of the eight was lying throughout.

The twist: one suspect is an accomplice — every statement they make is false.

Cracked by 7 detectives so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · FL — floor lamp · FO — flower bush · G — grandfather clock · P — potted plant · S — statue · T — telescope · W — window (square stays free)

The testimony

What each person said. One of these 8 is the killer's accomplice and every word they said is false — but not which one, not yet.

Simon and the Curator were in different rooms.
Xavier was beside the carpet. if true, leaves 3 of 50
Show it on the board
The squares this one statement leaves Xavier: 3 of 50.
Xavier was somewhere west of Beatrix.
Marina and Wilfred were in different rooms.
Marina was in the same row as the grandfather clock. if true, leaves 5 of 50
Show it on the board
The squares this one statement leaves Marina: 5 of 50.
Marina was in the same column as the statue. if true, leaves 1 of 50
Show it on the board
The squares this one statement leaves Marina: 1 of 50.
Felix was in the same row as the carpet. if true, leaves 7 of 50
Show it on the board
The squares this one statement leaves Felix: 7 of 50.
Felix was in the same column as the potted plant. if true, leaves 1 of 50
Show it on the board
The squares this one statement leaves Felix: 1 of 50.
Beatrix was somewhere north of Felix.
Beatrix was somewhere north of the Curator.
Beatrix was somewhere south of Elena.
Elena was in the same column as the desk. if true, leaves 6 of 50
Show it on the board
The squares this one statement leaves Elena: 6 of 50.
Wilfred was in the same column as the grandfather clock. if true, leaves 44 of 50
Wilfred was touching the outer wall. if true, leaves 24 of 50

Show the squares Xavier had left

The squares still open to Xavier once their own statements are taken into account — 3 of 50.

Unmasking the liar

One of these 8 people is the killer's accomplice, and every word they said is false — but you are not told which. Take each in turn: read their statements backwards and ask whether the rest of the testimony can still be satisfied.

If Simon were the one lying, no arrangement satisfies the rest. Not them.
If Xavier were the one lying, no arrangement satisfies the rest. Not them.
If Marina were the one lying, no arrangement satisfies the rest. Not them.
If Felix were the one lying, no arrangement satisfies the rest. Not them.

Another 3 candidates collapse the same way.

Only Wilfred survives the test. That is the accomplice, and everything they said is now read backwards.

Read backwards, Wilfred actually told you:

Wilfred was NOT in the same column as the grandfather clock.
Wilfred was NOT touching the outer wall.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Simon can only be in Terrace (row 6, column 1) — down from 50 possible squares.
Xavier can only be in Office (row 3, column 5) — down from 3 possible squares.
Beatrix can only be in Dome (row 2, column 7) — down from 50 possible squares.
Elena can only be in Office (row 1, column 8) — down from 6 possible squares.
Ivan can only be in Lounge (row 8, column 2) — down from 50 possible squares.
Wilfred can only be in Lounge (row 7, column 3) — down from 24 possible squares.

The answer

That leaves one arrangement, and one person who could have done it: Wilfred, in Lounge (row 7, column 3). Wilfred lied throughout and was never charged.

Show the solved board

The only arrangement the testimony allows. Wilfred is ringed in red.

Hard · time attack — The Old Observatory

A 10×8 grid across 7 rooms: Office, Cellar, Terrace, Lounge, Garden, Workshop, Archive. Fourteen statements, seventeen squares nobody could stand on, almost as many rooms as suspects, so a room claim nearly names a square, and one round of assume-and-test after elimination ran dry.

Cracked by one detective so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. A — armchair (square stays free) · B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · FL — floor lamp · FO — flower bush · G — grandfather clock · SO — sofa (square stays free) · ST — statue · TE — telescope · TR — tree · W — window (square stays free)

The testimony

What each person said, and how much of the board it rules out.

Ximena was in the same row as the floor lamp. leaves 8 of 67 squares
Show it on the board
The squares this one statement leaves Ximena: 8 of 67.
Ximena was in the same column as the carpet. leaves 1 of 67 squares
Show it on the board
The squares this one statement leaves Ximena: 1 of 67.
Ximena was all alone in a room.
Katia was in the same row as the carpet. leaves 15 of 67 squares
Show it on the board
The squares this one statement leaves Katia: 15 of 67.
Katia was beside the floor lamp. leaves 1 of 67 squares
Show it on the board
The squares this one statement leaves Katia: 1 of 67.
Dante was in the same column as the armchair. leaves 7 of 67 squares
Show it on the board
The squares this one statement leaves Dante: 7 of 67.
Dante was not seated on anything. leaves 6 of 67 squares
Show it on the board
The squares this one statement leaves Dante: 6 of 67.
Selma was in the same row as the grandfather clock. leaves 8 of 67 squares
Selma was exactly 1 column east of Bruno.
Bruno was somewhere east of the Curator.
Horacio was beside the window. leaves 1 of 67 squares
Wilfred was in the same row as the sofa. leaves 9 of 67 squares
Wilfred was all alone in a room.
Nobody was in the terrace.

Show the squares Dante had left

The squares still open to Dante once their own statements are taken into account — 6 of 67.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Dante can only be in Lounge (row 5, column 3) — down from 6 possible squares.
Selma can only be in Archive (row 6, column 9) — down from 8 possible squares.
Wilfred can only be in Office (row 7, column 4) — down from 9 possible squares.

The squares that had to be tested

The rest does not fall out on its own. It takes 3 eliminations of the same move: put someone on a square, follow the consequences, and watch the board contradict itself.

Had Lidia stood in Garden (row 1, column 8), Bruno would have had nowhere left to stand. So not there.
Put Bruno in Garden (row 4, column 8) and the testimony cannot be satisfied at all. So not there.

Show what goes wrong

Suppose Lidia stood on the dashed square. Bruno then has nowhere left to stand: every square still open to them is shaded out.

Another 1 squares fell the same way.

The answer

That leaves one arrangement, and one person who could have done it: Bruno, in Garden (row 1, column 8).

Show the solved board

The only arrangement the testimony allows. Bruno is ringed in red.

Expert — The Old Observatory

A 9×9 grid across 7 rooms: Cellar, Dome, Library, Archive, Lounge, Terrace, Office. Twenty statements, eighteen squares nobody could stand on, and two rounds of assume-and-test after elimination ran dry — and one of the nine was lying throughout.

The twist: one suspect is an accomplice — every statement they make is false; the accusation also demands the motive, not just the name.

Cracked by 6 detectives so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. A — armchair (square stays free) · B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · FL — floor lamp · FO — flower bush · G — grandfather clock · P — potted plant · S — sofa (square stays free) · T — telescope · W — window (square stays free)

The testimony

What each person said. One of these 9 is the killer's accomplice and every word they said is false — but not which one, not yet.

Sol was in the same row as the armchair. if true, leaves 8 of 67
Show it on the board
The squares this one statement leaves Sol: 8 of 67.
Sol was somewhere east of Yolanda.
Sol was somewhere west of Frida.
Yolanda was somewhere east of Ursula.
Yolanda was in the same row as the window. if true, leaves 8 of 67
Show it on the board
The squares this one statement leaves Yolanda: 8 of 67.
Xavier and the Journalist were in different rooms.
Xavier was somewhere east of Dorian.
Xavier was in the same column as the armchair. if true, leaves 8 of 67
Show it on the board
The squares this one statement leaves Xavier: 8 of 67.
Ursula was in the same column as the crate. if true, leaves 7 of 67
Show it on the board
The squares this one statement leaves Ursula: 7 of 67.
Ursula was somewhere west of the Chauffeur.
Ursula was in the same row as the bookshelf. if true, leaves 1 of 67
Show it on the board
The squares this one statement leaves Ursula: 1 of 67.
Frida was in the same column as the window. if true, leaves 17 of 67
Show it on the board
The squares this one statement leaves Frida: 17 of 67.
Jonas was somewhere north of Xavier.
Oscar was in the same row as the crate. if true, leaves 7 of 67
Oscar was in the same column as the floor lamp. if true, leaves 1 of 67
Dorian was in the same row as the sofa. if true, leaves 53 of 67
Dorian was somewhere east of the Doctor.
Exactly 2 people were in the lounge.
Exactly 2 people were in the archive.
Exactly 2 people were in the telescope dome.

Show the squares Sol had left

The squares still open to Sol once their own statements are taken into account — 8 of 67.

Unmasking the liar

One of these 9 people is the killer's accomplice, and every word they said is false — but you are not told which. Take each in turn: read their statements backwards and ask whether the rest of the testimony can still be satisfied.

If Sol were the one lying, no arrangement satisfies the rest. Not them.
If Yolanda were the one lying, no arrangement satisfies the rest. Not them.
If Xavier were the one lying, no arrangement satisfies the rest. Not them.
If Queralt were the one lying, no arrangement satisfies the rest. Not them.

Another 4 candidates collapse the same way.

Only Dorian survives the test. That is the accomplice, and everything they said is now read backwards.

Read backwards, Dorian actually told you:

Dorian was NOT in the same row as the sofa.
Dorian was NOT east of the Doctor.

The squares that had to be tested

The rest does not fall out on its own. It takes 96 eliminations of the same move: put someone on a square, follow the consequences, and watch the board contradict itself.

Had Sol stood in Dome (row 3, column 5), Xavier would have had nowhere left to stand. So not there.
Had Yolanda stood in Dome (row 2, column 4), Xavier would have had nowhere left to stand. So not there.
Put Xavier in Dome (row 2, column 4) and the testimony cannot be satisfied at all. So not there.
Had Queralt stood in Archive (row 1, column 1), Xavier would have had nowhere left to stand. So not there.

Show what goes wrong

Suppose Sol stood on the dashed square. Xavier then has nowhere left to stand: every square still open to them is shaded out.

Another 92 squares fell the same way.

The motive

This case demands the why as well as the who: naming the killer without proving the motive counts for nothing. 8 motives are in play, and these statements narrow them.

Oscar's motive would have been blackmail.
Sol's motive would have been ambition.
Xavier's motive would have been inheritance.
Yolanda's motive would have been debts.
Jonas's motive would have been jealousy.
Frida was not driven by buried secrets.
Frida was not driven by obsession.

The answer

That leaves one arrangement, and one person who could have done it: Frida, in Lounge (row 5, column 7). Dorian lied throughout and was never charged.

The only motive left standing for Frida is revenge.

Show the solved board

The only arrangement the testimony allows. Frida is ringed in red.

Expert · time attack — The Old Observatory

A 9×9 grid across 7 rooms: Library, Office, Garden, Workshop, Lounge, Cellar, Terrace. Sixteen statements, seventeen squares nobody could stand on, and two rounds of assume-and-test after elimination ran dry — and one of the nine was lying throughout.

The twist: one suspect is an accomplice — every statement they make is false; the accusation also demands the motive, not just the name.

Cracked by one detective so far.

How this case was cracked — the full solution to this board, step by step

Every step below is the solver’s own — the same one that proved this board has exactly one answer. The counts are real: you can check them against the grid.

Lettered squares are objects. Most take the square out of play — which is why the counts above are of free squares, not of all of them — but the ones marked below do not: their square is still in play. A — armchair (square stays free) · B — bookshelf · CA — carpet (square stays free) · CH — chest · CR — crate · D — desk · FL — floor lamp · FO — flower bush · G — grandfather clock · P — potted plant · S — statue · TE — telescope · TR — tree · W — window (square stays free)

The testimony

What each person said. One of these 9 is the killer's accomplice and every word they said is false — but not which one, not yet.

Percy and the Butler were in different rooms.
Percy was in the same row as the desk. if true, leaves 60 of 68
Cesar was in the same column as the telescope. if true, leaves 8 of 68
Show it on the board
The squares this one statement leaves Cesar: 8 of 68.
Victor was somewhere north of Kurt.
Victor was in column 5. if true, leaves 8 of 68
Show it on the board
The squares this one statement leaves Victor: 8 of 68.
Victor was somewhere south of Percy.
Kurt was in the same column as the statue. if true, leaves 8 of 68
Show it on the board
The squares this one statement leaves Kurt: 8 of 68.
Zaida was somewhere north of Cesar.
Zaida was in the same column as the desk. if true, leaves 6 of 68
Show it on the board
The squares this one statement leaves Zaida: 6 of 68.
Yolanda was in the same row as the crate. if true, leaves 6 of 68
Show it on the board
The squares this one statement leaves Yolanda: 6 of 68.
Yolanda was somewhere south of the Professor.
Julian was somewhere east of the Curator.
Julian was somewhere south of the Professor.
Julian was in the same row as the potted plant. if true, leaves 6 of 68
Show it on the board
The squares this one statement leaves Julian: 6 of 68.
Queralt was in the same column as the flower bush. if true, leaves 8 of 68
Exactly 3 people were in the library.

Show the squares Zaida had left

The squares still open to Zaida once their own statements are taken into account — 6 of 68.

Unmasking the liar

If Cesar were the one lying, no arrangement satisfies the rest. Not them.
If Victor were the one lying, no arrangement satisfies the rest. Not them.
If Kurt were the one lying, no arrangement satisfies the rest. Not them.
If Zaida were the one lying, no arrangement satisfies the rest. Not them.

Another 4 candidates collapse the same way.

Only Percy survives the test. That is the accomplice, and everything they said is now read backwards.

Read backwards, Percy actually told you:

Percy and the Butler were in the SAME room.
Percy was NOT in the same row as the desk.

What the testimony settles on its own

Nobody shares a row or a column, so each placement narrows everyone else. Before a single guess:

Queralt can only be in Library (row 1, column 6) — down from 8 possible squares.

The squares that had to be tested

The rest does not fall out on its own. It takes 80 eliminations of the same move: put someone on a square, follow the consequences, and watch the board contradict itself.

Had Percy stood in Workshop (row 2, column 3), Zaida would have had nowhere left to stand. So not there.
Had Cesar stood in Workshop (row 3, column 1), Percy would have had nowhere left to stand. So not there.
Had Victor stood in Library (row 3, column 5), Percy would have had nowhere left to stand. So not there.
Had Kurt stood in Garden (row 4, column 9), Yolanda would have had nowhere left to stand. So not there.

Show what goes wrong

Suppose Percy stood on the dashed square. Zaida then has nowhere left to stand: every square still open to them is shaded out.

Another 76 squares fell the same way.

The motive

This case demands the why as well as the who: naming the killer without proving the motive counts for nothing. 8 motives are in play, and these statements narrow them.

Zaida's motive would have been jealousy.
Yolanda's motive would have been inheritance.
Cesar's motive would have been debts.
Julian's motive would have been revenge.
Queralt's motive would have been buried secrets.
Whoever did it was not driven by blackmail.
Victor was not driven by obsession.

The answer

That leaves one arrangement, and one person who could have done it: Victor, in Office (row 7, column 5). Percy lied throughout and was never charged.

The only motive left standing for Victor is ambition.

Show the solved board

The only arrangement the testimony allows. Victor is ringed in red.

How to read a case above

The grid size is the size of the crime scene, so a 10×9 expert case is a far larger search than a 5×5 beginner one — but the difficulty is really carried by the clues, not the square count. A beginner case tells you almost directly where somebody stood. An expert case tells you where somebody was not, three times, and expects you to do the rest — and on half of them one of those statements is a lie told to protect the killer. If a case lists a motive, naming the right person is not enough on its own; you have to prove why.

How to play · Solving cases with a liar · Techniques

The day in review

Five Empty Chairs — The accomplice at The Old Observatory is charged: 6 independent detectives put the same name to the same lie.

The Old Observatory set the scene for all ten investigations on 12 September 2026, offering puzzles that ranged from straightforward room layouts to intricate deceptions. In the standard untimed cases, matters grew increasingly complicated as the grid expanded. While the 5x5 beginner, 6x6 easy, and 7x7 medium boards kept things honest, a liar entered the fray across the 8x8 hard case with its six rooms, where six of eight players found the truth. The 9x9 expert investigation pushed further, demanding both motive deduction and sorting through lies across seven rooms, ultimately yielding three solutions from six attempts.

Across the timed boards, the pressure mounted even when the rooms were quiet. Time attack investigators worked through a four-room 5x5 beginner layout, a 6x6 easy grid, a 7x7 medium setup, and an expansive 10x8 hard grid featuring seven rooms. The final time attack case returned to a 9x9 expert framework, once again requiring detectives to uncover a motive and expose a liar among its seven rooms.

One name dominated the record books across every single assignment of the day. Chentian claimed the fastest time in all ten cases, clocking 0m 09s on the untimed beginner, 0m 11s on easy, 0m 18s on medium, 3m 05s on hard, and 6m 01s on expert. In the time attack division, chentian secured the sole completed records, posting 0m 10s on beginner, 0m 20s on easy, 0m 38s on medium, 1m 08s on hard, and 6m 26s on the taxing expert case.

Fastest detectives of the day

Beginner: chentian — 0m 09s · Easy: chentian — 0m 11s · Medium: chentian — 0m 18s · Hard: chentian — 3m 05s · Expert: chentian — 6m 01s · Beginner · time attack: chentian — 0m 10s · Easy · time attack: chentian — 0m 20s · Medium · time attack: chentian — 0m 38s · Hard · time attack: chentian — 1m 08s · Expert · time attack: chentian — 6m 26s

The solutions

The solved boards — spoilers for every case of 12 September 2026

Key: red ring = the murderer · amber dashes = the lying accomplice · ✕ = the victim · initials mark where each suspect was proved to stand.

Beginner — The Old Observatory

Ines (journalist) is in custody — the case was closed by 11 detectives.

Easy — The Old Observatory

Petra (heiress) ended the day behind bars — convicted by 9 detectives.

Medium — The Old Observatory

Felix (curator) was named and charged; 9 detectives closed this one.

Hard — The Old Observatory

The cell door shut on Wilfred (curator), on the evidence of 6 detectives. Wilfred lied for them and was never charged.

Expert — The Old Observatory

3 detectives put Frida (journalist) away before the day was out. The motive — revenge — was proved along with the name. Dorian lied for them and was never charged.

Beginner · time attack — The Old Observatory

Dora (chef) is in custody — the case was closed by one detective.

Easy · time attack — The Old Observatory

Felix (gardener) ended the day behind bars — convicted by one detective.

Medium · time attack — The Old Observatory

Celeste (diva) was named and charged; one detective closed this one.

Hard · time attack — The Old Observatory

The cell door shut on Bruno (magician), on the evidence of one detective.

Expert · time attack — The Old Observatory

one detective put Victor (curator) away before the day was out. The motive — ambition — was proved along with the name. Percy lied for them and was never charged.

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Every day's cases — the calendar · ← the cases for 11 September

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