In this detective novel, the young doctor Humphrey Jardine stumbles upon a corpse during a walk near Hampstead Heath in the middle of the night. However, when he returns to the spot with a police officer, the corpse has disappeared. And this is just the start of a series of strange and sometimes life threatening events. Had it really been a dead man he had seen? And if so, who was it? And what is the role of the mysterious Mrs. Samway, who keeps popping up wherever he goes? He will need the help of Dr. John Thorndyke to solve this mystery. This is the fourth novel featuring R. Austin Freeman's famous detective Dr. John Thorndyke. The preceding ones are also available on LibriVox: The Red Thumb Mark, the Eye of Osiris (a.k.a. the Vanishing Man, both titles on LV) and The Mystery of 31 New Inn. (Summary by Anna Simon)