A disgraced former commander re-enlists in the Royal Navy during the Second World War and is put in command of the antiquated "four pipe" World War I ship, HMS ''Ballantrae'', formerly USS ''Whittier'', one of the Town-class destroyers from the Destroyers for Bases Agreement. He and his crew become an efficient fighting force in the process, prior to being sent on ''Operation Boadicea'', a daring suicide mission against a Nazi submarine base on the coast of France.