Violent Playground centres on a Liverpool street gang led by Johnny Murphy (McCallum).

When local Juvenile Liaison Officer Sergeant Truman (Baker) visits the Murphy household, with the view that if you catch kids at an early age, they will end up being reseponsible adults. Truman becomes romantically involved with Johnny’s sister and also finds considerable points of similarity between his previous investigations into the activities of an arsonist know as the ‘Firefly’ and his investigation of Johnny.