The apparent accidental drowning of Sir William Ponson in the Cranshaw River is revealed to be murder, initiating a complex investigation by Scotland Yard. Inspector Tanner faces the challenge of suspects with seemingly unbreakable alibis, while a crucial fifth individual, whose footprints were found at the scene, remains elusive. The narrative unfolds through Tanner's methodical pursuit of clues, navigating the constraints of alibis and the mystery of the unknown man, all within the confines of a classic Golden Age detective framework.

The Ponson Case, a rediscovered work by Freeman Wills Crofts, is presented as a significant find from the Golden Age of detective fiction. As the second novel by a writer once lauded as ‘The King of Detective Story Writers,’ it offers a chance to engage with his foundational style. The introduction by Dolores Gordon-Smith, herself an author of Golden Age mysteries, situates the book within its historical and literary context, highlighting its value for enthusiasts of the genre. This re-release allows modern readers to experience the intricate plotting and methodical detection that characterized Crofts's celebrated contributions to crime literature.