The Black Files · October 29, 2026 · Difficulty: Master Detective

Black File #140 — SolutionThe Last Witness

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The case

Grace Brennan, ad sales rep, was found dead at The Gazette Newsroom at 9:20 PM. Seven people were at the scene. Exactly one of them was alone with Grace in the same zone.

The answer

The killer: Carla Patel, alone with Grace Brennan in the Bullpen.

Nothing is forced until you test Bridget at C1, D1, E1, B2, D2, E2, F2, B3, C3, D3, E3, F3, B4, C4, D4 or E4: every wrong cell ends in a contradiction (an empty row or column, or the two-people rule). With Bridget at E4 the rest cascades and leaves Carla alone with Grace in the Bullpen.

Step-by-step deduction

1. Before placing anyone, each clue eliminates cells:
2. • Evelyn: was standing on the floor; Bridget was farther north than Evelyn, and Bridget is at least at row 1; column A belongs to Frances; was in the same zone as Frances, and Frances can only be in the Bullpen or the Print Shop. Remaining: E2, D3, B4 and B5.
3. • Frances: was the westernmost person of all, and since there is one person per column somebody occupies column A: that is Frances. Remaining: A1, A2, A3, A5 and A6.
4. • Carla: was sitting on the sofa. Remaining: D1, D2, B3, E3, G4, D5, G5 and C7.
5. • Daniel: was standing on the floor; Bridget was farther west than Daniel, and Bridget is at least at column B; was farther north than Audrey, and Audrey is no farther than row 7. Remaining: C1, E2, D3, G3, D4, E4, C5 and E6.
6. • Still wide open: Bridget (16), Audrey (31) and Grace (35) possible cells; they close as the others are placed.
7. At this point no cell is forced. Time to test a hypothesis. Try Bridget, who can only be at C1, D1, E1, B2, D2, E2, F2, B3, C3, D3, E3, F3, B4, C4, D4 or E4.
8. – Bridget at C1: forces Daniel at E2, and then Grace would be alone in the Archive, with nobody who could be the killer. Impossible.
9. – Bridget at D1: forces Daniel at E2, and then row 7 would be left empty. Impossible.
10. – Bridget at E1: Daniel is left with no possible cell. Impossible.
11. – Bridget at B2: Audrey is left with no possible cell. Impossible.
12. – Bridget at D2: Daniel is left with no possible cell. Impossible.
13. – Bridget at E2: Daniel is left with no possible cell. Impossible.
14. – Bridget at F2: Daniel is left with no possible cell. Impossible.
15. – Bridget at B3: Bridget is left with no possible cell. Impossible.
16. – Bridget at C3: Daniel is left with no possible cell. Impossible.
17. – Bridget at D3: Daniel is left with no possible cell. Impossible.
18. – Bridget at E3: Bridget is left with no possible cell. Impossible.
19. – Bridget at F3: Bridget is left with no possible cell. Impossible.
20. – Bridget at B4: Bridget is left with no possible cell. Impossible.
21. – Bridget at C4: forces Evelyn at B5, and then Audrey is left with no possible cell. Impossible.
22. – Bridget at D4: forces Evelyn at B5 and Audrey at F7, and then Daniel is left with no possible cell. Impossible.
23. – Bridget at E4: everything fits: it yields Daniel at G3 and Evelyn at B5.
24. So Bridget goes to E4, Daniel goes to G3 and Evelyn goes to B5.
25. Again, nothing is forced. Try Audrey, who can only be at C6 or F7.
26. – Audrey at C6: Grace is left with no possible cell. Impossible.
27. – Audrey at F7: everything fits: it yields Carla at D2, Frances at A6 and Grace at C1.
28. So Audrey goes to F7, Carla goes to D2, Frances goes to A6 and Grace goes to C1.
29. With all seven placed, the only people in the Bullpen are Grace and Carla: Carla was alone with the victim.

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