It is the fourth novel with the mysterious Albert Campion, aided as usual by his butler/valet/bodyguard Magersfontein Lugg and his policeman friend Stanislaus Oates.

When Albert Campion is called in by the fiancee of an old college friend to investigate the disappearance of her uncle, he little expects the mysterious spate of death and dangers that follows among the bizarre inhabitants of Socrates Close, Cambridge.

Campion is waiting for a client, Joyce Blount, the fiancee of his solicitor friend Marcus Featherstone, and when she arrives she clearly recognises Oates' stalker, but denies having seen him before.

He meets William, and learns that Oates' mysterious stalker was Cousin George, who visits rarely and has some power over Great-Aunt Caroline.

Uncle William approaches Marcus, telling him he has been suffering from blackouts, and Campion also finds the old man's service revolver is missing, along with some cord from the same (unused) room.

The film also featured Mary Morris (in her last role; she died some months before it was broadcast)[1] as Great-aunt Caroline and Timothy West as William.