Why had I, a mere passer-by, been called in so suddenly to be taken into the intimacy of the millionaire's household? Was it by mere accident that I had been invited in, or was it by careful design? I had lost five thousand pounds by foolish speculation, and yet I had regained it by being party to a criminal offence. Again, who was the pretty, dark-haired girl who had first uttered those hysterical screams, and then, while fully dressed, had died upon Mrs. De Gex's bed? Further, if the mysterious dead girl had been niece of the millionaire surely my friend the caretaker would have known her? I confess that I now became more bewildered than ever. That a girl named Gabrielle Engledue--whoever she might have been--had died, and that I had forged a certificate showing the cause of death were hard, solid facts. But the mystery of it all was complete. That I had been the victim of some very carefully prepared and subtle plot was apparent, and it had become my own affair to investigate it and bring to justice those who were responsible for the poor girl's death. Time after time I questioned the caretaker regarding the existence of the millionaire's niece, Miss Engledue, but it was plain to me that he had no knowledge of any such person. "Was there not a death in this house--about five weeks ago?" I asked. "Death?" he echoed. "Why, no, sir. You must be dreaming. If there had been a death while I was away, either my wife or I would certainly have heard about it." And he looked suspiciously at me as though he believed I had taken leave of my senses. An hour later I was back at Rivermead Mansions, where Harry, for whom I had left a note, was awaiting me. As we sat together before a cheerful fire I told him of my lapse into unconsciousness, of my loss of memory, but I did not explain all that had happened, for, as a matter of fact, I had no desire that anyone should know of my guilt in posing as a medical man and thus becoming implicated in the mysterious death of Gabrielle Engledue. My friend sat and heard me, smoking his pipe in silence. "Extraordinary!" he said. "You ought to go to the police, Garfield. You were doped--without a doubt. But what was the motive? I've been very worried about you. When you had been missing a week they sent over from your office, and I then went to the police at Hammersmith. They made every inquiry and circulated your description. But they could discover no trace of you. I'll have to report that you've been found." "Yes, do so to-morrow morning," I urged. "I don't want the police following me about--thank you," and I laughed, rather grimly perhaps. During the hours that I lay awake that night a thought suddenly crossed my mind--an idea which next day I promptly put into execution.