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One Week in the Underground Shelter (illustration)
FILE No.3Unsolved

One Week in the Underground Shelter

Difficulty ★★☆about 5 minLocked Rooms & Impossible CrimesWhat is not writtenEntries and exits
A man was found stabbed in a sealed shelter with one lift. Sort out who is known to have used it.

Case Record

Miura, a wealthy man, built a small underground room in the basement of his mountain villa that doubles as a nuclear shelter. Its only entrance is a lift connecting it to the surface. It has no window and no hidden passage.

Miura invited his friends Fujita and Harada and, calling it “an experiment on a week of life in a closed space,” sent the two underground. Food and water were sent down on the lift every day.

After seven days, Fujita’s body was found underground. There were stab wounds from a blade. Harada was distraught and could barely speak.

Investigation confirmed the following:

  • Miura has not once ridden the lift since the experiment began.
  • Harada has not once ridden the lift since the experiment began.
  • Nothing that could serve as a weapon was underground at the start of the experiment, and none was brought down afterward.
Your question

Fujita was found underground where there was no weapon. Given these conditions, what course of events is possible?

Case Files

Evidence

Diagram

Diagram

Timeline

  1. Miura sends Fujita and Harada underground and starts the experiment.
  2. Food and water are sent down by lift every day.
  3. Fujita is found underground. Harada is distraught.

Hints

If you get stuck, open the hints one at a time, in order.

Open hint 1

Organize the confirmed conditions person by person.

Open hint 2

Who and who are confirmed not to have used the lift?

Open hint 3

What is “not written” can be a clue too.

Solve It

Your question

Fujita was found underground where there was no weapon. Given these conditions, what course of events is possible?

Choose the answer closest to the truth.

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The Truth

Fujita went up once, was stabbed on the surface and was returned underground

The answer is “Fujita went up once, was stabbed on the surface and was returned underground.”

For Miura and Harada, it is confirmed that they did not ride the lift after the experiment began. But nothing is written about Fujita. If Fujita was stabbed on the surface and sent back down on the lift, the scene can be explained without bringing a weapon underground. Options 1 and 4 break the weapon condition, and option 3 breaks the condition about Miura’s movements. Still, this information does not identify the culprit.

What can be saidA weapon was not brought undergroundMiura and Harada never rode the liftFujita’s use is not writtenAnswer: Fujita went up, was stabbed, and was returned
Diagram of the solution

Key Points

  • Separate what is confirmed from what is not written
  • Use the weapon condition (none brought in)
  • Notice that one person’s movements are not written

Why people get fooled

Your eyes go to the two suspects, and you overlook that nothing has been confirmed about the third person’s use of the lift.

Similar tricks

  • The type where what is not written is the clue
  • Locked-room reasoning that organizes entries and exits

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If you view the truth, this case will not count as solved on your own. Open it anyway?

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