A Polish sailor on leave, Korchinsky (Horst Buchholz), heads into Tiger Bay to visit his girlfriend, Anya (Yvonne Mitchell). He finds that she is now living with another man and guns her down in a fit of anger. Their noisy argument attracts the attention of 12-year-old Gillie (Hayley
Mills), a lonely tomboy who witnesses the murder through a mail slot. She gets hold of the murder weapon, convinced that having a gun will make her popular with her peers when they play cowboys and Indians. In time, the precocious youngster is confronted by a police detective (her real-life
father, John Mills), but she frustrates him by reciting a convincing string of lies that get her...