"Have you noticed anything suspicious about the place to-night?" asked Smith.
"I have!" was the startling reply. "That accounts for your finding me where you did. My usual post is in the lobby. But about eleven o'clock, when the theater people began to come in, I had a hazy sort of impression that someone or something slipped past in the crowd—something that had no business in the hotel."
We got out of the lift.
"I don't quite follow you," said Smith. "If you thought you saw something entering, you must have formed a more or less definite impression regarding it."
"That's the funny part of the business," answered the man doggedly. "I didn't! But as I stood at the top of the stairs I could have sworn that there was something crawling up behind a party—two ladies and two gentlemen."
"A dog, for instance?"
"It didn't strike me as being a dog, sir. Anyway, when the party passed me, there was nothing there. Mind you, whatever it was, it hadn't come in by the front. I have made inquiries everywhere, but without result." He stopped abruptly. "No. 189—Mr. Guthrie's door, sir."
Smith knocked.
"Hallo!" came a muffled voice; "what do you want?"
"Open the door! Don't delay; it is important."