All the Dr. Thorndyke books are outstanding. This one is no exception. In this installment, the action centers on one Dr. Humphrey Jardine, who is the narrator of the story, and who himself is the focus of several strange events. Jardines troubles begin with a casual walk, where he comes across the body of a man and runs to fetch the police, only to come back and find that the dead man has disappeared. The police can find no trace that the man was ever there, so Jardine takes it upon himself to examine the scene for clues. His findings lead him into a very strange adventure which can only be solved with the technical expertise of Dr. Thorndyke, but not before Jardine finds his life in danger, and not just once.