While walking in London’s al fresco pleasure exchange, the Row, one bright spring afternoon, exchanging salutes with those I knew, a brilliantly-varnished carriage, drawn by a magnificent pair of bays, suddenly passed me. Notwithstanding the rapid pace at which it was driven, I caught a glimpse of the tip of a tiny bronze shoe stretched against the cushion of the front seat, the fold of a light fawn dress, and under a lace-fringed sunshade a fair face—the face of Agàfia Ivanovna, Princess Tchikhatzoff.

Until the equipage turned out of the Park, I kept it in sight; then I jumped into a hansom, and followed, until I watched her alight and enter one of the largest houses in Queen’s Gate. On inquiry, I ascertained that the house had been taken furnished for the season by a young foreign lady, whose name nobody seemed to know.

That evening, after dining at the club, I sat in the smoking-room, shrinking with horror from some terrible deed that I seemed forced to commit. Then gradually there crept over me that strange attraction that drew me irresistibly towards her; until at last, unable to remain, I put on my hat and drove to the house.

“I wish to see the Princess,” I said, giving my card to the grave, elderly man-servant who opened the door.

Bowing, he ushered me into a small, well-furnished room and disappeared. The moment he had gone, I heard voices speaking rapidly in Russian in the next apartment. Agàfia was addressing some man, and I thought I heard her utter my name, and refuse to see me. The rooms communicated by means of folding-doors, and, determined to speak with her, I turned the handle and entered.

The scene that met my gaze was only momentary, but it was one of tragedy. In a low lounge chair a young man was sitting, calmly smoking a cigarette. He had blonde hair, but his face was turned from me. Stealthily Agàfia crept up behind him, her face distorted by the same terrible look of vengeance that I had sometimes seen in my weird day-dreams. In her uplifted hand something gleamed in the lace-shaded lamplight. It was the knife upon which she had taken the ikon oath in Petersburg.

“Princess! At last!” I cried, rushing forward in an endeavour to prevent her from striking the deadly blow at her unsuspecting visitor.

At that moment, however, I felt my hands gripped tightly, and a man flung himself before me. With an imprecation, I tried to push him aside, for I had instantly recognised him as the man who had dined with the Princess at the Dominique.

My senses seemed paralysed. With one hand he held me, and with the thumb and finger of the other he pressed my temples so tightly that I became dazed. For a moment I was conscious of his sinister face peering into mine, and of a peal of harsh, demoniacal laughter that rang through the room. Then I knew no more.

When I recovered consciousness, I found myself lying in bed in a long hospital ward, with the kind face of my friend, Dr Ferguson, a specialist in mental diseases, looking down upon me.