"In his hurry he might have left the towel in the paper, intending to destroy it later."
Kennedy frowned. "That's possible, Walter. I had not thought of that. Still"—he brightened—"I'm counting on human nature. I don't believe anyone guilty of the crime could have that towel in his possession, after the hints I have thrown out, without examining it so as to see what telltale mark or stain would be apt to betray his identity."
"You can see that Manton's the logical man?"
"It would be easy for anyone else to follow and observe us."
"Then—?"
"First of all we must keep an eye out for any person showing signs of the itching concoction. We must observe anyone with noticeably clean hands. Principally, however, another thing worries me."
"What's that, Mr. Kennedy?" asked Mackay.
"Walter and I found a cigarette case belonging to Jack Gordon in the basement; also a butt smoked three-quarters of the way down and left directly in the negative room. The fire doors between the different film vaults, which are arranged like the safety compartments in a ship, were all open. I want to know why Gordon was down there and—well, I seem to sense something wrong."
"Good heavens! Craig," I interposed. "You don't attach any importance to the fact that those doors were open!"
"Walter, in a case of real mystery the slightest derangement of matters of ordinary routine is a cause for suspicion."