And I pointed to the writing table.

"Let's go back to the Grange Park burglaries for a moment," Quarles began slowly. "We have investigated them under the impression that they were the work of a gang, but it is possible they were worked by one man. The gang may have attacked Clarence Lodge, Crosland's chance though excellent marksmanship accounting for one of the members while the rest escaped; but on the whole the evidence seems to suggest that this man was alone, and we might conclude that the burglaries were the work of one man."

"I shall never believe that," I said.

"Still, you cannot disprove it by direct evidence. You may show it to be unlikely, but you cannot prove it impossible. Indirectly we can go a little further. There were several features about these burglaries to make them remarkable. The right house was chosen, the thieves were never heard or seen, there were always plenty of misleading clues left about, there was no bungling, In the case of Clarence Lodge the wrong house was chosen—Crosland himself told us that it contained no jewelry or particular valuables. The thieves, or rather thief, was heard, the sound must have been considerable to arouse both Crosland and his sister; the thief makes no attempt to conceal himself and fires the moment he is spoken to; in short, there was a considerable amount of bungling, quite unlike the experts we have been thinking of. We are safe, therefore, I fancy, in considering that the Clarence Lodge affair is not to be reckoned as one of the Grange Park burglaries."

I shook my head doubtfully.

"Since experts may at times make mistakes, I grant that my negative evidence is not as convincing as it might be," said Quarles, "but I want the point conceded. I want, as it were, a base line upon which to build my theoretical plan. I want to forget the burglaries, in fact, and come to the Clarence Lodge case by itself. So we have a dead man and we first ask who shot him. Crosland says he did, and tells us the circumstances, his sister confirms his statement, and the butler, the woman servant and the nurse, who are quickly upon the stage in this tragedy, see no reason to disbelieve the statement. We burrow a little deeper into the evidence, and we discover one or two interesting facts. The man was shot on the left side of the head, a clean wound above the left ear. Crosland says he fired after he had been fired at, so the man, directly he had fired, must deliberately have turned his head to the right, which at least is remarkable. Further, to hit the wall of the landing in the place he did the man must have stood in the very center of the stairs to fire. His body was found some feet away from this central position, and a bullet so fired and striking where it did could not have missed two people standing on that landing. I have made a rough plan here," and Quarles took up the papers from the table, "giving the position of the dead man, the position of the walls and stairs. The lines show where the bullet would have hit if fired from a spot nearer where the dead man was found."

I examined his diagram closely.

"A man shot through the brain might fall several feet away from where he was standing," I said.

"Yes, behind where he was standing, or perhaps forward, but hardly to one side. However, we burrow again, and we try and answer Zena's question why it was Helen Crosland who ran for the police. Why not? we may ask. Her close association with her brother in the affair, her anxiety on his account, make it natural that she should dash out not only for help but to make it certain that they had nothing to hide. Her words to Poulton, 'The burglars, and I am afraid my brother has shot one of them,' are significant. They tell the whole story in a nutshell. Crosland's statement merely elaborates it, over-elaborates it, in fact. The bolts on the front door, Wigan, were very stiff; I tried them. Helen Crosland would certainly have had difficulty in drawing them back, and it is an absurdity for her brother to declare that she had gone before he knew what she was doing."

I had no comment to make, and Zena leaned forward in her chair, evidently excited.