A seemingly harmless prank involving an alarm clock leads to a complex web of international intrigue and murder at a country house party. When a young man dies under suspicious circumstances after a game of 'Seven Dials,' his friends begin an investigation that pulls them into a dangerous conspiracy involving secret societies and high-stakes espionage. The narrative follows a group of amateur sleuths as they navigate the rigid social structures of 1920s England while attempting to outmaneuver elusive criminals. The story unfolds through a third-person perspective that emphasizes witty dialogue and the methodical unmasking of hidden identities.

This novel is frequently cited as a lighter, more adventurous entry in the author's extensive bibliography, often compared to her 'Tommy and Tuppence' series. Readers typically appreciate the blend of humor and suspense, noting that the plot prioritizes entertainment and clever twists over gritty realism. The work is regarded as a quintessential example of the interwar period's fascination with secret societies and international intrigue. While some critics point to the convoluted nature of the conspiracy, the general consensus highlights the charm of the characters and the brisk, engaging pacing of the mystery.