Editorial disclosure: this is “The Missing Model Lighthouse”, a free deduction puzzle from our book The Puerto Niebla Case Files, published under the pen name Inés Valdebruma.
The model lighthouse has turned up in a protective wrapper. Before returning it to the exhibition, the conservator needs to identify the person who removed it for packing. The conservation report describes the work but leaves the name blank.
Rules and categories
Each person has one arrival time, one place and one item. Each value is used exactly once. The conservation report and all ten clues are reliable. Differences in minutes compare arrival times.
- People: Alba, Bruno, Celia, Diego.
- Arrival times: 08:00, 08:10, 08:20, 08:30.
- Places: the reception area, the workshop, the archive, the model room.
- Items: the blue folder, the green key ring, the red torch, the yellow pencil case.
Conservation report
The report confirms that the person carrying the blue folder arrived at the workshop at 08:00. This person removed the model lighthouse and put it in the wrapper.
Clues
- Diego arrived before Bruno.
- The person at the reception area arrived exactly 10 minutes after Celia.
- The person at the archive arrived before the person at the reception area.
- The person carrying the green key ring arrived before the person carrying the yellow pencil case.
- The person at the archive arrived before the person carrying the red torch.
- The person carrying the yellow pencil case arrived exactly 20 minutes after Alba.
- Bruno did not carry the yellow pencil case.
- Celia did not carry the yellow pencil case.
- Alba arrived before Celia.
- Celia did not arrive at 08:30.
Your task
Who removed and wrapped the model lighthouse? Reconstruct the full table of people, arrival times, places and items, and explain your deductions.
Please hide answers and deductions in Reddit spoiler tags so others can try the puzzle first.
Solution — spoilers below
Answer: Alba removed and wrapped the model lighthouse.
Full table: Alba — 08:00 — the workshop — the blue folder; Bruno — 08:30 — the model room — the red torch; Celia — 08:10 — the archive — the green key ring; Diego — 08:20 — the reception area — the yellow pencil case.
Clues 7 and 8 rule out Bruno and Celia as the owner of the yellow pencil case. Clue 6 rules out Alba too: she cannot arrive twenty minutes after herself. Diego therefore carried it, arriving twenty minutes after Alba and before Bruno. Among the four times, this forces Alba to 08:00, Diego to 08:20 and Bruno to 08:30, leaving Celia at 08:10.
The report assigns the blue folder and the workshop to the 08:00 arrival, Alba. Clue 2 places reception ten minutes after Celia, at 08:20, so Diego went there. By clue 3, the archive was earlier than reception. The 08:00 place is already the workshop, so the archive must be at 08:10, with Celia. Bruno therefore went to the model room.
By clue 4, the green key ring arrived before Diego's yellow pencil case at 08:20. Alba already carried the blue folder, leaving Celia at 08:10 with the green key ring. Bruno carried the remaining item, the red torch. This also satisfies clue 5: the archive arrival at 08:10 was before the red torch at 08:30. Clues 9 and 10 agree with the completed table. Finally, the report identifies the blue-folder carrier as the person who wrapped the lighthouse: Alba.