A lighthearted house party prank turns lethal when a notorious late-sleeper is found dead, triggering a high-stakes investigation into a mysterious criminal organization. Lady Eileen 'Bundle' Brent, a spirited and inquisitive socialite, takes it upon herself to uncover the truth behind the suspicious death of Gerry Wade. As she navigates the upper-crust social circles of England, she encounters a web of international intrigue and secret societies that threaten to silence her permanently. The narrative unfolds with a blend of witty banter and suspenseful pacing, following the amateur sleuth as she attempts to decipher the significance of the missing alarm clock and the cryptic 'Seven Dials' moniker.

This novel is widely recognized as a stylistic departure for Christie, leaning heavily into the adventure-thriller genre rather than her traditional locked-room puzzles. Readers often note the successful fusion of comedic social commentary with the darker undercurrents of international espionage. The character of Bundle Brent is frequently cited as a highlight, providing a sharp and energetic focal point for the unfolding mystery. While some critics point to the plot's reliance on coincidence, the consensus remains that the book serves as an entertaining and fast-paced example of early twentieth-century genre blending.