This novel is the latest in the series featuring Riley Fitzhugh. With the advent of the Second World War Fitzhugh leaves his private detective business in Los Angeles and joins the Navy. He goes through officer training and gets assigned to the PC 475, an anti U-boat vessel. The 475 is nicknamed The Nameless by her crew, because patrol craft were only given numbers. The ship patrols the Gulf of Mexico during the early days of the war. Fitzhugh and the Nameless uncover and destroy German supply station in northern Cuba and track the crew of a damaged U boat. Along the way Fitzhugh has a few adventures in Havana, where he meets both Ernest Hemingway and his glamorous wife, Martha Gellhorn.