Greig and Crofts call on a boy, who had been nicked previously as a pick pocket, because they want to talk to him about burglaries. When they arrive, the boy calls them in because his mother has been assaulted by his father. The boy sold a stolen brooch to a man so he could use the money for his mother. Donna comes up with a link with the burlaries to an alarm firm - 3 of the houses only had dummy boxes. Greig and Crofts visit the security firm manager who mentions a lad in the firm also plays with the boy with the brooch. Lines talks to the mother as he is now handling the assault case. The victim couldn't give a reason for the attack but previous attacks have been over very little. Her son was also hit.
