“This, Chief. I happen to know about this edition of De Sade's ‘Justine.’ It is not very common, though it is very famous; perhaps I had better say ‘infamous.’ The original edition was in ten small volumes with one hundred illustrations—illustrations as bad as the text. The author, a pathological case, spent most of his time in insane asylums, sent there first by Napoleon. He was not insane, however, in the strict sense of the word. Now, as I said, there were ten volumes. The secretary said that the last eight volumes of the set Mr. Warren had were bound two to a book; the first two were not.”

There was a perplexed look on the chief's face. He was trying to follow Bartley, but did not seem to understand just what it was all about. Seeing this, Bartley explained:

“What I mean is this. Mr. Warren's set contained six bound books. Five of them, the girl said, were bound in white vellum. The first volume was bound in red morocco. That case was locked during the afternoon. Some one smashed the glass, so it could not have been Mr. Warren who took the books. They took what they thought was the entire set or edition. But they made a mistake, a natural one—”

“What was that?” came the chief's insistent voice.

“A very logical and very simple mistake. They saw the books were all bound in white vellum; so they were—all but the first volume—that was red morocco. They took the five books thinking they had the set, but left the red one behind. No doubt they were so upset they did not think of looking very closely. But they took the books all right. That is what is missing from the room.”

“But, my God, Mr. Bartley,” broke in the chief, “no one would murder a man for five books.”

Bartley laughed. “If you knew the history of crime, Chief, you would know there have been several murders over a book. One man not only killed his best friend to secure the possession of a rare book he had, but burned his house after the crime. Yet in a sense you are right. I fail to understand why any one should kill Warren for this particular set.”

“Are they worth much?” I asked.

He shook his head. “Not much as rare books go. The work has been reprinted under cover. You can buy it for about twenty-five dollars in Europe. I doubt if the original edition is worth over two hundred. And the type of man who would steal that sort of a book after committing a murder is—”

Suddenly he paused as if a new thought had suddenly come to him, but what it was he did not say. There came the voice of the chief, and there was such a complaining tone in his voice that I almost laughed.