Sgt. Bob Cryer is approaching his 30th year of service, but some of the senior officers at the station doubt he is still up to the job. Supt. Chandler assigns Cryer the difficult task of resolving a situation where a group of prostitutes are at loggerheads with a local residents group led by Counciller Angela Morris. Cryer suggests a 'zone of tolerance', a non-residential area where the prostitutes can work without upsetting the locals, and manages to convince the girls to give it a try. As Chandler heads off to a charity dinner, a call comes through that the Morris' house has been torched. Meanwhile, PC Smith attends his interview for transfer to SO19 - he is successful, and leaves Sun Hill to join the Armed Response Unit.

When the victim in yesterday's domestic disturbance turns up badly beaten and left for dead, her husband is adamant he had nothing to do with it. Mandy tells Cryer that the woman who was bashed, Cath Evans, was working as a prostitute, and that the Councillor's husband Justin was one of her clients. But Justin in turn, having admitted his deeds to his wife, says that he was seeing Mandy as well, and that on the night of the fire, she turned up late and had blood on her clothes. Meanwhile, Smith arrives at SO19 to find his new friend Julie also made the grade, but on their training course, treats her as the token female. When she beats him on the rifle range it causes friction, and their boss cautions that they have to learn to work as a team.

Sgt. Cryer and PC Hayward attend an incident at a local school where an angry divorcee, Chris Finnessey, is demanding to see his son. When the boy's teacher warns the police of Finnessey's violent reputation and a possible restraining order against him, he grabs a Stanley knife and takes the teacher and Sgt. Cryer hostage. Faced with an armed suspect and two hostages, Supt. Chandler calls in SO19, although the only Trojan unit available is that of the newly-qualified PC Smith and PC Stanley. When Finnessey and his son leave the school building, Chandler gives authorisation to fire. Smith shoots first but to his horror, accidentally hits Cryer. Stanley takes down Finnessey. Cryer survives the shooting, but his career in the police is over.