This novel details the story of a high-ranking Russian submarine captain who aims to defect to the United States without sparking a war between the two nations. The American government, upon receiving information about the captain's intentions, sends its best analyst to aid in the successful defection of the captain and his crew. The novel is a thrilling tale of espionage, filled with suspense and detailed technical descriptions of military technology and procedure.

Set in the 1920s, the novel is a clever blend of murder mystery and romance, revolving around a dentist who, in a bid to escape his dreary life and loveless marriage, plans to run away with his mistress on an ocean liner to America. However, his plan goes awry when he is mistaken for a famous detective, the titular Inspector Dew. As he plays along with the charade, a murder occurs on board the ship, and he is unwittingly thrust into the role of solving the crime. The story unfolds with a series of twists and turns, combining humor and suspense as the protagonist navigates through the unexpected complications of his new identity.