Twenty-fourth in the long-running mystery series with Dr Launcelot Priestley.

After the inquest in the port town of Blacksand concludes that the death of Major Walter Bedworthy was an accident due to drowning, his friend summons in Priestley due to his belief that it was in fact murder. This proves to be the case when the dead man's brother is also found drowned a few days later. Assisted by Superintendent Hanslet and Inspector Waghorn of Scotland Yard, Priestley sets out to unmask the cunning killer.