Keeping Mum is the 670th episode of The Bill.
D.S. Greig and W.P.C. Croft call on a teenage boy, who had been arrested previously as a pickpocket, because they want to talk to him about burglaries. When they arrive, the boy calls them in because his mother has been assaulted. The boy sold a stolen brooch to a man so he could use the money for his mother. W.P.C. Harris comes up with a link between the burglaries and an alarm firm: three of the houses only had dummy boxes. Greig and Croft visit the security firm manager who mentions that an employee knows the boy with the brooch. D.C. Lines talks to the mother as he is now handling the assault case: the victim won't give a reason for the attack, but previous attacks have been over very little. Her son was also hit. Lines and D.C. Woods talk to a publican to find out where the husband lives. During the interview the husband claims to have no respect from his family and denies the assault. The victim wants to drop the charges because it turns out that her son is responsible.