“Not a toy,” replied Mr. Merritt, “but an ornament. A useful ornament; for it is the head of one of those jewelled hat-pins that have been so fashionable of late. A dagger with the hilt encrusted with precious stones is quite a common design.”

“Did you find the pin itself?” I asked.

“No, I did not,” the detective answered regretfully.

“How do you account for the handle being where you found it?”

“I think that in all probability the pin was removed from the body immediately after it had done its work, and in doing so the head was wrenched off. During the excitement which followed no one noticed where it fell, and its loss was not discovered till the victim had been disposed of. Young Derwent evidently expected the place to be searched, which accounts for the care with which he tried to remove all traces of his presence, and his extreme anxiety to find this, which, he feared, if discovered on the premises, might prove a sure clue. Now, that theory hangs together pretty well, don’t it?” wound up the detective.

Without answering him, I inquired: “And what do you mean to do now?”

“I’m afraid I shall have to arrest Miss Derwent, as we can find no trace of her two companions. By the way, it is as you supposed;—the man you saw leaving the building was no tradesman, so he is probably the person we want. I have, therefore, given his description to the police, and hope soon to have some news of him.”

“So, Mr. Merritt, you would really arrest a girl on such flimsy evidence, and for a crime you do not believe her to have committed?” I inquired indignantly.

“As for the evidence, I think it is fairly complete,” answered the detective, “and I would not arrest Miss Derwent if I were not convinced that she is implicated in this affair, and think that this is the surest way of getting hold of the precious couple. I can’t allow a criminal to slip through my fingers for sentimental reasons, and every hour’s delay renders their escape more possible. The girl may be innocent,—I believe she is; but that one of that trio is guilty I am perfectly sure.”

“Are you, really?” I exclaimed. “Well, I am not, and, if you will listen to me for a few minutes, I think I can easily prove to you that you are wrong. For since Friday I, too, have thought of a new and interesting point in connection with this case.” The detective looked indulgently at me.