Common Mistakes

When a case will not come out, or a placement turns out wrong, the cause is almost never a missing technique. It is a clue read slightly wrongly, or a rule forgotten for a moment. These are the ones that catch people most often, roughly in order of how often they do.

Reading “North Of” as “Directly Above”

“North of Dana” means in a higher row than Dana — any higher row, in any column. It does not mean the tile directly above her, and it does not even mean the same column; two people can never share a column anyway. The tight version exists as its own clue: “exactly one column west of Bella” fixes the distance. If a compass clue seems to place someone too quickly, check that you have not quietly turned it into an offset.

Forgetting That the Victim Takes a Line

The victim has no clue, so it is easy to leave them out of the counting. But the victim stands on a tile like everyone else and uses a row and a column of their own. A row that seems to have room for two suspects may in fact have room for one suspect and the victim. Count people, not suspects.

“Beside” Across a Wall

“Beside a table” means on a tile directly next to it — left, right, above or below — and in the same room. A tile on the other side of a wall is not beside anything in the next room, however close it looks. The same holds for windows and doors: beside a window means on the tile whose wall carries the window. Diagonal tiles never count as beside.

Closing a Group Too Early

Locked lines are powerful, which makes them dangerous. Two suspects only lock two rows if every single tile either of them could still occupy lies in those rows. One stray possibility — a tile in row 8 you had not crossed out yet — and the lock does not exist. Before striking out a whole row on the strength of a group, check each member’s list in full.

Treating a Forced Tile as a Placement

When a row has only one open tile left, someone must stand there — but not necessarily the suspect you were thinking about. The tile is occupied; by whom is still open. Cross out the column through it for everyone else, but do not place a particular person on it until their own list says so.

Forgetting the Murder Rule

The victim is alone with exactly one suspect. A room with two suspects already in it cannot be the victim’s room, and a suspect with an “alone” clue can never be the murderer. When a case is nearly finished and will not close, the murder rule is the first thing to check.

Reasoning About the Victim’s Looks

Only the victim’s gender is shown. Their hair, glasses and everything else are hidden on purpose, and no clue ever depends on them. If your reasoning needs to know whether the victim wore glasses, it has gone wrong somewhere earlier.

Cases to Practise On

The longest medium cases in the casebook — long enough for every one of these mistakes to tempt you:

More Strategy

The Techniques

Keep Going