ield some one? Who is this man that engaged Number
Seven?"

Gritz shook his head unhappily. "I don't know his name."

"You don't know his name?" thundered Coquenil.

"We have to be discreet in these matters," reasoned the other. "We have
many clients who do not give us their names, they have their own reasons
for that; some of them are married, and, as a man of the world, _I_ respect
their reserve." M. Gritz prided himself on being a man of the world. He had
started as a penniless Swiss waiter and had reached the magnificent point
where broken-down aristocrats were willing to owe him money and sometimes
borrow it--and he appreciated the honor.

"But what do you call him?" persisted Coquenil. "You must call him
something."

"In speaking to him we call him 'monsieur'; in speaking of him we call him
'_the tall blonde_.'"

"The tall blonde!" repeated M. Paul.

"Exactly. He has been here several times with a woman he calls Anita.
That's all I know about it. Anyway, what difference does it make since he
didn't come to-night?"

"How do you know he didn't come? He had a key to the alleyway door, didn't
he?"

"Yes, but I tell you he sent a _petit bleu_."

The detective shrugged his shoulders. "_Some one_ has been here and locked
this door on the inside. I want it opened."

"Just a moment," trembled Gritz. "I have a pass key to the alleyway door.
We'll go around."

"Make haste, then," and they started briskly through the halls, the
proprietor assuring M. Paul that only a single key was ever given out for
the alleyway door and this to none but trusted clients, who returned it the
same night.

"Only a single key to the alleyway door," reflected, Coquenil.

"Yes."

"And your 'tall blonde' has it now?"

"I suppose so."

They left the hotel by the main entrance, and were just going around into
Rue Marboeuf when the _concierge_ from across the way met them with word
that Caesar had arrived.

"Caesar?" questioned Gritz.

"He's my dog. Ph-h-eet! Ph-h-eet! Ah, here he is!" and out of the shadows
the splendid animal came bounding. At his master's call he had made a
mighty plunge and broken away from Papa Tignol's hold.

"Good old fellow!" murmured M. Paul, holding the dog's eager head with his
two hands. "I have work for you, sir, to-night. Ah, he knows! See his eyes!
Look at that tail! We'll show 'em, eh, Caesar?"

And the dog answered with delighted leaps.

"What are you going to do with him?" asked the prop