Sleuthic

The Black Files · October 1, 2026 · Difficulty: Rookie

Black File #112 — SolutionCurtain Call

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The case

Benjamin Mercer, producer, was found dead at Palace Theater at 8:40 PM. Seven people were at the scene. Exactly one of them was alone with Benjamin in the same zone.

The evidence (12 clues)
  1. Erica was sitting on the sofa.
  2. Alvin was sitting on the sofa.
  3. Dennis was standing on the floor.
  4. Grace was the westernmost person at the scene.
  5. Alvin was farther west than Floyd.
  6. Erica was farther west than Alvin.
  7. Floyd was farther west than Clifford.
  8. Grace was farther north than Floyd.
  9. Erica was farther west than Dennis.
  10. Alvin was farther north than Grace.
  11. Erica was farther north than Clifford.
  12. Alvin was farther north than Dennis.

The answer

The killer: Erica Gallagher, alone with Benjamin Mercer in the Box Office.

Fixing rows and columns from the extreme-position clues cascades through the board and leaves Erica alone with Benjamin in the Box Office.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Alvin: was sitting on the sofa; was farther west than Floyd, and Floyd is no farther than column G; Erica was farther west than Alvin, and Erica is at least at column C; was farther north than Grace, and Grace is no farther than row 6. Only D2 is left.
  3. • Benjamin: row 6 already belongs to Grace; column A already belongs to Grace; nobody else can occupy row 1, so it must be Benjamin; column D already belongs to Alvin; column C already belongs to Erica; nobody else can occupy column B, so it must be Benjamin. Only B1 is left.
  4. • Clifford: Floyd was farther west than Clifford, and Floyd is at least at column D; Erica was farther north than Clifford, and Erica is at least at row 3; row 6 already belongs to Grace; row 7 belongs to Floyd; nobody else can occupy row 4, so it must be Clifford; nobody else can occupy column G, so it must be Clifford. Only G4 is left.
  5. • Dennis: was standing on the floor; Erica was farther west than Dennis, and Erica is at least at column C; Alvin was farther north than Dennis, and Alvin is at least at row 2; row 6 already belongs to Grace; column D already belongs to Alvin; row 3 already belongs to Erica; row 7 belongs to Floyd. Only E5 is left.
  6. • Erica: was sitting on the sofa; was farther west than Alvin, and Alvin is no farther than column D; was farther north than Clifford, and Clifford is no farther than row 7; row 6 already belongs to Grace; column A already belongs to Grace. Only C3 is left.
  7. • Floyd: Alvin was farther west than Floyd, and Alvin is at least at column C; was farther west than Clifford, and Clifford is no farther than column G; Grace was farther north than Floyd, and Grace is at least at row 6; row 6 already belongs to Grace; column D already belongs to Alvin; column E already belongs to Dennis. Only F7 is left.
  8. • Grace: was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Grace; was farther north than Floyd, and Floyd is no farther than row 7; Alvin was farther north than Grace, and Alvin is at least at row 2. Only A6 is left.
  9. That already places Grace at A6, Alvin at D2, Erica at C3, Benjamin at B1, Clifford at G4, Dennis at E5 and Floyd at F7.
  10. With all seven placed, the only people in the Box Office are Benjamin and Erica: Erica was alone with the victim.
Solved map of Black File #112: Alvin D2, Benjamin B1, Clifford G4, Dennis E5, Erica C3, Floyd F7, Grace A6
The solved map: Alvin D2, Benjamin B1, Clifford G4, Dennis E5, Erica C3, Floyd F7, Grace A6.

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