The Red Widow Murders is a modern mystery with a shuddering historic background. The scene is laid in Lord Mantling's mansion on Curzon Street, in a room called the Red Widow's Chamber. In 1802, a man had died there; in 1825, a girl; in 1870 and 1876, two gentlemen were mysteriously found dead. Then the room had been sealed up.

Now, many years later, eight men and a woman gathered around a table for a sinister experiment. Among them are Sir Henry Merrivale, the rumbling, grumbling, grand old man who has become one of our best-loved detectives; Lord Mantling of the flaming hair and booming voice; Guy Brixham, his brother, sardonic and uneasy behind his glasses; Ravelle, the blond Frenchman, smiling and debonair; little, inoffensive Bender. Which one of them would draw the Ace of Spades and be escorted into the Red Widow's Chamber? Is it a death trap? ...Poison? ... Or WHAT?