Investigations of a large scale hijacking operation from transport trucks leads to small time criminal 'Buttercup' Sands. At his home, shared with his de facto wife Edie, the police discover an autistic child, Monty, who is confined to his room by a leg rope. His mother tells police it is the only way she can control him. The child also has a crippled leg which the mother believes is due to the child's autism, but a chiropractor, Tony Carboni, is convinced there is a spinal complaint. Later, the boy runs away and inadvertently helps police stumble on a vital clue when they have to rescue him from an abandoned mine shaft.