After retired U.S. officer Robert Taine (Joel McCrea) believes he has accidentally shot and killed a poacher, he comes upon two strangers, Hiart (Marius Goring) and his driver, Diss, and is unaware that they are spies who have actually murdered the man. Polish operative Sandorski (Herbert Lom), a British intelligence aide, recruits Bob and his wife, Cecily (Evelyn Keyes), to prevent Hiart, Diss and their British contact, Magda, from reaching a scientist vital to foreign enemy interests.