The Black Files · October 24, 2026 · Difficulty: Elite

Black File #135 — SolutionThe Break Room

Missed the case? Play Black File #135 →

The case

Felix Mercer, data analyst, was found dead at Hartwell Research Lab at 6:05 AM. Seven people were at the scene. Exactly one of them was alone with Felix in the same zone.

The answer

The killer: Glen Marsh, alone with Felix Mercer in the Bench Area.

Nothing is forced until you test Benjamin at E1, E2, D3, G3, C4, D5 or G5: every wrong cell leaves someone with no possible cell. With Benjamin at G3 the rest cascades and leaves Glen alone with Felix in the Bench Area.

Step-by-step deduction

1. Before placing anyone, each clue eliminates cells:
2. • Diane: was on the stairs; Glen was farther west than Diane, and Glen is at least at column B; Colin was farther north than Diane, and Colin is at least at row 1. Remaining: D2, D4, E5 and C6.
3. • Andre: was on the stairs; Glen was farther north than Andre, and Glen is at least at row 1. Remaining: A2, D2, B3, D4, E5 and C6.
4. • Benjamin: was sitting in a chair; was farther north than Andre, and Andre is no farther than row 6. Remaining: E1, E2, D3, G3, C4, D5 and G5.
5. • Still wide open: Glen (13), Evelyn (18) and Colin (29) possible cells; they close as the others are placed.
6. At this point no cell is forced. Time to test a hypothesis. Try Benjamin, who can only be at E1, E2, D3, G3, C4, D5 or G5.
7. – Benjamin at E1: row 5 would be left empty. Impossible.
8. – Benjamin at E2: column G would be left empty. Impossible.
9. – Benjamin at D3: column G would be left empty. Impossible.
10. – Benjamin at G3: everything fits.
11. – Benjamin at C4: forces Andre at E5 and Diane at E5, and then Diane is left with no possible cell. Impossible.
12. – Benjamin at D5: Benjamin is left with no possible cell. Impossible.
13. – Benjamin at G5: forces Andre at C6 and Diane at C6, and then Diane is left with no possible cell. Impossible.
14. So Benjamin goes to G3.
15. Again, nothing is forced. Try Felix, who can only be at A1, B1, C1, A2, D2, E2, A4, C4, E6, F6, A7, B7, E7 or F7.
16. – Felix at A1: forces Evelyn at B7 and Colin at F2, and then row 6 would be left empty. Impossible.
17. – Felix at B1: forces Colin at F2 and Evelyn at A7, and then row 6 would be left empty. Impossible.
18. – Felix at C1: row 7 would be left empty. Impossible.
19. – Felix at A2: forces Evelyn at B7, and then row 6 would be left empty. Impossible.
20. – Felix at D2: forces Evelyn at A7 and Glen at B1, and then Andre is left with no possible cell. Impossible.
21. – Felix at E2: forces Evelyn at A7, Glen at B1, Andre at C6, Colin at F5 and Diane at C6, and then Diane is left with no possible cell. Impossible.
22. – Felix at A4: everything fits: it yields Evelyn at B7, Diane at E5, Glen at D2, Andre at C6 and Colin at F1.
23. – Felix at C4: Diane is left with no possible cell. Impossible.
24. – Felix at E6: Diane is left with no possible cell. Impossible.
25. – Felix at F6: column C would be left empty. Impossible.
26. – Felix at A7: Felix would be alone in the Sample Vault, with nobody who could be the killer. Impossible.
27. – Felix at B7: Felix would be alone in the Sample Vault, with nobody who could be the killer. Impossible.
28. – Felix at E7: Felix would be alone in the Sample Vault, with nobody who could be the killer. Impossible.
29. – Felix at F7: Felix would be alone in the Sample Vault, with nobody who could be the killer. Impossible.
30. So Evelyn goes to B7, Felix goes to A4, Diane goes to E5, Glen goes to D2, Andre goes to C6 and Colin goes to F1.
31. With all seven placed, the only people in the Bench Area are Felix and Glen: Glen was alone with the victim.

Play today's case →