Michael O'Hara (Orson Welles) meets the beautiful blonde Elsa (Rita Hayworth) as she rides a horse-drawn coach in Central Park. Three hooligans waylay the coach. Michael rescues Elsa and escorts her home. Michael reveals he is a seaman and learns Elsa and her husband, disabled criminal defence attorney Arthur Bannister (Everett Sloane), are newly arrived in New York City from Shanghai. They are on their way to San Francisco via the Panama Canal. Michael, attracted to Elsa despite misgivings, agrees to sign on as an able seaman aboard Bannister's yacht and begin an adventure.