“Yes. They were fastened from the inside.”

“How many of them did you try?”

“All three of them.”

“Sure of that, sir?”

“I’m in the habit of being sure. Why do you ask?”

“That’s a funny thing,” said the superintendent.

“What’s a funny thing?”

“When the crime was discovered this morning, the middle one was open⁠—not latched, that is to say.”