Therefore, in putting my next question to you, I consider that I am
addressing it to a tried detective."

"I will answer your question, Monsieur le Prefet, to the best of
my ability."

"Here it is, then: Supposing that there were at this moment in the safe
an object of some kind, a jewel, let us say, a diamond out of a tie pin,
and that this diamond had come from a tie pin which belonged to somebody
whom we knew, somebody who had spent the night in this house, what would
you think of the coincidence?"

"There we are," said Perenna to himself. "There's the trap. It's clear
that they've found something in the safe, and next, that they imagine
that this something belongs to me. Good! But, in that case, we must
presume, as I have not touched the safe, that the thing was taken from me
and put in the safe to compromise me. But I did not have a finger in this
pie until yesterday; and it is impossible that, during last night, when I
saw nobody, any one can have had time to prepare and contrive such a
determined plot against me. So--"

The Prefect of Police interrupted this silent monologue by repeating:

"What would be your opinion?"

"There would be an undeniable connection between that person's presence
in the house and the two crimes that had been committed."

"Consequently, we should have the right at least to suspect the person?"

"Yes."

"That is your view?"

"Decidedly."

M. Desmalions produced a piece of tissue paper from his pocket and took
from it a little blue stone, which he displayed.

"Here is a turquoise which we found in the safe. It belongs, without a
shadow of a doubt, to the ring which you are wearing on your finger."

Don Luis was seized with a fit of rage. He half grated, through his
clenched teeth:

"Oh, the rascals! How clever they are! But no, I can't believe--"

He looked at his ring, which was formed of a large, clouded, dead
turquoise, surrounded by a circle of small, irregular turquoises, also of
a very pale blue. One of these was missing; and the one which M.
Desmalions had in his hand fitted the place exactly.

"What do you say?" asked M. Desmalions.

"I say that this turquoise belongs to my ring, which was given me by
Cosmo Mornington on the first occasion that I saved his life."

"So we are agreed?"

"Yes, Monsieur le Prefet, we are agreed."

Don Luis Perenna began to walk across the room, reflecting. The movement
which the two detectives made toward the two doors told hi