Facts nobody disputes:
1. Each guest rode the elevator down to the lobby exactly once that night, from their own floor. The stairwell doors are alarmed, and the alarm never sounded.
2. A power flicker at 1:50 a.m. froze the log. The safe was opened during that flicker, and the thief rode down during it. Exactly one ride took place in the gap, and it left no entry.
The elevator log, which records the floor where the car stopped for each rider:
1:05 a.m., floor 4
1:20 a.m., floor 2
1:35 a.m., floor 5
1:50 a.m., no entry (power flicker)
2:10 a.m., floor 1
The front desk adds these clues:
A. Doyle rode down immediately before Ellis, with no other ride between them.
B. Abbott’s room is on an odd-numbered floor.
C. Brandt and Doyle have rooms on neighboring floors, one directly above the other.
D. Cruz was not the first to ride down.
E. Doyle’s room is on a lower floor than Cruz’s.
Who emptied the safe, and which floor does each guest live on?
💡 Hint
The log is a skeleton, not a gap: five riders and five floors constrain it. Fix the ride order by floor first, then use the back-to-back clue to branch into cases.
Reveal answer
Brandt took the brooches. The floors are Abbott 1, Ellis 2, Brandt 3, Doyle 4 and Cruz 5.
Step-by-step solution
- Each guest rode once from a different floor, so the five rides cover floors 1 to 5. The log shows floors 4, 2, 5 and 1 for the first, second, third and fifth rides. The unlogged fourth ride must have come from floor 3. The ride order by floor is therefore 4, 2, 5, 3, 1, and the thief lives on floor 3.
- Clue A: Doyle rode right before Ellis. Back-to-back rides are floors (4, 2), (2, 5), (5, 3) or (3, 1). Clue E puts Doyle below Cruz, so Doyle cannot be on 5, which removes (5, 3). Three cases remain.
- Case 1: Doyle on 4, Ellis on 2. Cruz must be above Doyle, so Cruz is on 5. Brandt is next to Doyle (clue C), so Brandt is on 3, because 5 is taken. Abbott gets floor 1, which is odd (clue B). Cruz rode third, so clue D holds. All fit.
- Case 2: Doyle on 2, Ellis on 5. The remaining floors are 1, 3 and 4 for Abbott, Brandt and Cruz. Cruz must live above Doyle, Abbott must be on an odd floor, and Brandt must be next to Doyle (floor 1 or 3), so Cruz ends up on floor 4. But floor 4 was the first ride, which breaks clue D. Case 2 fails.
- Case 3: Doyle on 3, Ellis on 1. Abbott needs an odd floor, and only 5 is left among 2, 4 and 5, so Abbott is on 5. Cruz must be above Doyle, so Cruz is on 4, which is again the first ride. Clue D fails. Case 3 fails.
- Only Case 1 survives. The fourth ride came from floor 3, and Brandt lives on floor 3. Brandt took the brooches. A brute-force check of every arrangement confirms it is the only one.
Why it fools people
The one record that matters seems to be missing. In truth the hole is the most informative part of the log: with five riders and five floors, four known entries leave only one possibility for the fifth. We tend to read a gap as blankness rather than as a constraint. Beginning with the log gives a fixed skeleton that every clue can be tested against, while beginning with names invites guessing.
Did you get it?
About This Puzzle
The Lakeshore Hotel stands a few blocks from the Chicago River, an old brick building with five guest floors, one room per floor. On a windy night in March, the night manager found the office safe open and a velvet pouch of antique brooches gone. The office camera had been unplugged for cleaning, so the only record of movement is the elevator’s own log. That log has a hole in it, and the inspector believes the hole is the whole story.
How to Think About It
A grid puzzle is won by narrowing, not guessing. Start with what the log tells you for certain, because it fixes the order of the floors before you know a single name. Then let the most restrictive clue carve the problem into a few cases. Work each case to its end; one that breaks a clue is gone. Keep a tidy table of floors against names. When only one case survives, check it against all five clues one last time.
Common Traps
The loudest trap is the missing entry itself. It is tempting to think the gap hides information, when in fact it is a deduction waiting to happen if you count carefully. Another is to start placing people on floors before the ride order is settled, which leads to a tangle of half-finished guesses. People also treat a clue as spent after one case. A clue such as “not the first to ride” can eliminate several arrangements, so check it against every case.
Where This Puzzle Comes From
This case belongs to the family of logic grid puzzles, a staple of American puzzle magazines. Golden Age detective fiction followed a “fair play” idea: the reader sees every clue the detective uses. This original case follows that spirit.
Try This Variation
Suppose the front desk loses clue B, so you no longer know that Abbott’s room is on an odd floor. Everything else, including the log, is unchanged. Can you still name the thief?
Show the answer to the variation
No. Without clue B, four different worlds fit the log and the remaining clues, and they point to three different thieves: Brandt, Doyle and Cruz. Clue B is what removes Cases 2 and 3 cleanly. It looks minor, yet the case needs it, which is typical of well-built grid puzzles: every clue earns its place.