Roy Walsh (James Kenney) is a brash and enterprising thug who bullies his friends (including Rene, played by a young Joan Collins) into subservience. He and his gang assault and rob people on the street, but things get increasingly dangerous when their behaviour escalates to larger crimes. Unafraid to tackle a host of taboo subjects, Cosh Boy is a penetrating portrait of postwar Britain and its simmering social tensions, and one of the first British films to receive an ‘X’ certificate.