Sleuthic

The Black Files · October 27, 2026 · Difficulty: Master Detective

Black File #138 — SolutionLights Out

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The case

Ernest Navarro, regular customer, was found dead at Marlow's Restaurant at 8:40 PM. Seven people were at the scene. Exactly one of them was alone with Ernest in the same zone.

The evidence (10 clues)
  1. Graham was sitting on a sofa.
  2. Bridget was the easternmost person at the scene.
  3. There was exactly one person in the Bar.
  4. Dana was farther west than Graham.
  5. Dana was farther north than Bridget.
  6. Franklin was farther west than Angela.
  7. Clifford was farther west than Graham.
  8. Clifford was farther north than Dana.
  9. Franklin was farther north than Graham.
  10. Bridget was farther north than Graham.

The answer

The killer: Graham Coleman, alone with Ernest Navarro in the Dining Room.

Nothing is forced until you test Dana at A2, A3, B3 or B4: every wrong cell leaves someone with no possible cell. With Dana at B4 the rest cascades and leaves Graham alone with Ernest in the Dining Room.

Step-by-step deduction

  1. Before placing anyone, each clue eliminates cells:
  2. • Bridget: was the easternmost person of all, and since there is one person per column somebody occupies column G: that is Bridget; Dana was farther north than Bridget, and Dana is at least at row 2; was farther north than Graham, and Graham is no farther than row 6. Remaining: G3, G4 and G5.
  3. • Dana: was farther west than Graham, and Graham is no farther than column C; was farther north than Bridget, and Bridget is no farther than row 5; Clifford was farther north than Dana, and Clifford is at least at row 1. Remaining: A2, A3, B3 and B4.
  4. • Graham: was sitting on the sofa; Dana was farther west than Graham, and Dana is at least at column A; Bridget was farther north than Graham, and Bridget is at least at row 2; there was exactly 1 person in the Bar, and those are already Bridget. Remaining: B5, C5, B6 and C6.
  5. • Clifford: was farther west than Graham, and Graham is no farther than column C; was farther north than Dana, and Dana is no farther than row 4. Remaining: A1, B1, A2, A3 and B3.
  6. • Still wide open: Franklin (18), Angela (22) and Ernest (27) possible cells; they close as the others are placed.
  7. At this point no cell is forced. Time to test a hypothesis. Try Dana, who can only be at A2, A3, B3 or B4.
  8. – Dana at A2: forces Clifford at B1, and then Franklin is left with no possible cell. Impossible.
  9. – Dana at A3: forces Clifford at B1, Angela at F2, Ernest at D7 and Franklin at D2, and then Franklin is left with no possible cell. Impossible.
  10. – Dana at B3: forces Ernest at D7, and then row 6 would be left empty. Impossible.
  11. – Dana at B4: everything fits: it yields Bridget at G5, Graham at C6, Ernest at D7, Angela at F2, Clifford at A3 and Franklin at E1.
  12. So Bridget goes to G5, Dana goes to B4, Graham goes to C6, Ernest goes to D7, Angela goes to F2, Clifford goes to A3 and Franklin goes to E1.
  13. With all seven placed, the only people in the Dining Room are Ernest and Graham: Graham was alone with the victim.
Solved map of Black File #138: Angela F2, Bridget G5, Clifford A3, Dana B4, Ernest D7, Franklin E1, Graham C6
The solved map: Angela F2, Bridget G5, Clifford A3, Dana B4, Ernest D7, Franklin E1, Graham C6.

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