Mrs. Bentley has been arrested for murder. The evidence is overwhelming: arsenic she extracted from fly papers was in her husband's medicine, his food and his lemonade, and her crimes are being plastered across the newspapers. Even her lawyers believe she is guilty. But Roger Sheringham, the brilliant but outspoken young novelist, is convinced that there is too much evidence against Mrs. Bentley and sets out to prove her innocence.

Investigating the disappearance of a vicar's daughter in London, the popular novelist and amateur detective Roger Sheringham is shocked to discover that the girl is already dead, found hanging from a screw by her own silk stocking. Reports of similar deaths across the capital strengthen his conviction that this is no suicide cult but the work of a homicidal maniac out for vengeance - a desperate situation requiring desperate measures.

Graham and Joan Bendix have apparently succeeded in making that eighth wonder of the modern world, a happy marriage. And into the middle of it there drops, like a clap of thunder, a box of chocolates. Joan Bendix is killed by a poisoned box of liqueur chocolates that cannot have been intended for her to eat. The police investigation rapidly reaches a dead end. Chief Inspector Moresby calls on Roger Sheringham and his Crimes Circle - six amateur but intrepid detectives - to consider the case.