At twenty-five minutes past, as the Prefect was lighting a cigar, the chief detective ventured to joke:
"That's something you will have to do without, next time, Monsieur le Préfet. It would be too risky."
"Next time," said M. Desmalions, "I shall not waste time in keeping watch. For I really begin to think that all this business with the letters is over."
"You can never tell," suggested Mazeroux.
A few minutes more passed. M. Desmalions had sat down. The others also were seated. No one spoke.
And suddenly they all sprang up, with one movement, and the same expression of surprise.
A bell had rung.
They at once heard where the sound came from.
"The telephone," M. Desmalions muttered.
He took down the receiver.
"Hullo! Who are you?"
A voice answered, but so distant and so faint that he could only catch an incoherent noise and exclaimed:
"Speak louder! What is it? Who are you?"
The voice spluttered out a few syllables that seemed to astound him.
"Hullo!" he said. "I don't understand. Please repeat what you said. Who is it speaking?"
"Don Luis Perenna," was the answer, more distinctly this time.
The Prefect made as though to hang up the receiver; and he growled:
"It's a hoax. Some rotter amusing himself at our expense."
Nevertheless, in spite of himself, he went on in a gruff voice:
