A 12-year-old Hayley Mills made her big-screen debut in this melodramatic thriller.
Mills plays Gillie, a young girl who lives in a British tenement. There, she accidentally sees a Polish sailor named Korchinsky kill his mistress in a fit of rage after he finds her with another man. Gillie retrieves the murder weapon, and tries to get away.
Korchinsky succeeds in catching up with the little girl, but he finds that he just cannot harm her. When this lonely duo forms an unlikely bond, Gillie realizes that she must mislead the police if she is to save her new-found friend..