A D.S. from the Drug squad is looking for the D.C.I. Cathy recognises him. He is interested in Cathy and follows her on her beat as she checks a domestic. He turns out to be her ex-husband who wants her back. The wife involved in the domestic had been beaten regularly before she stabbed her husband. Quinnan is mouthing off in the canteen and Cathy takes offense. Later Dave wants to patch things up with her. When Dave goes to the hospital he comes across Cathy being threatened by her ex who takes a swing at Dave.

The police are out on the streets of Sun Hill enforcing a crackdown on prostitution. P.C. Stamp nicks an underage tom named Suzanne, and W.P.C. Ackland cautions a would-be punter who mistakes her for a prostitute. An armed robbery at a local building society soon takes precedence. A security guard has been shot and wounded, and Ch. Supt. Brownlow, pending the arrival of PT17, authorises AFOs (Authorised Firearms Officers) Sgt. Cryer and P.C. Stamp to attend. P.C. Quinnan and W.P.C. Marshall locate the fleeing suspects and pursue them into a building site, but they come under fire from the shotgun wielding bandit. Cryer and Stamp arrive, and Cryer shouts a warning, but is forced to shoot and kill the robber (Skene) when he points the shotgun at Quinnan. It it later discovered by the S.O.C.O. that the shotgun was empty. Cryer's colleagues, including the police investigating the shooting are sympathetic and supportive of him, but Cryer seems deeply affected by the fact that he has taken a

Tony and Barry are stopped in the street by a man who says his flat has been burgled and the burglars are still on the premises. They surprise a flat owner who is in the bathroom. Tosh finds out the lady was lying about her whereabouts because she was with a married man. Delia visits an old man who wanted to report a prowler to an Inspector. He rings again and Delia chases a man to a car park on the Jasmine Allen. Delia and the old man are hit by a car.

The Metropolitan Police Serious Crimes Squad sweep into Sun Hill and commandeer the station's briefing room, setting a few noses out of joint in the process. They are there to investigate the murder of a police informant, who at the time of his death was under the protection of Sun Hill CID. DI Burnside and DS Roach come to blows when Roach refuses to share the blame for withdrawing officers from the safe house, and accuses Burnside of corruption.

The relief is reserve troops for a demonstration. It is very boring waiting on waste ground. At a meal break, Delia, Norika and June find a distressed probationer in the toilets. Tempers are getting strained. Young is starting to question why he is still on the job. On the way back to the station the van is attacked by youths with sticks and petrol bombs. All the windows are broken and someone's arm catches fire.

Monroe and the relief go to a pub where some men are damaging it. One of the men tries to blackmail Dave over some moonlighting Dave did to get off the charge. Monroe thinks the men might be involved in protection. Dave tells both Sgts Boyden and Maitland who advises him to tell Monroe. Dave asks Barry's advice as Fed Rep. Barry asks Reg's advice as he was previous Fed Rep.

When her car breaks down on the way to the station, DC Viv Martella misses an important CID briefing about an obbo on a suspected armed robbery, and is furious when she is taken off the case by DI Frank Burnside. As CID and SO19 wait outside the target, Martella and PC Tony Stamp follow up a simple case to arrest a suspected bag snatcher. As they wait outside the suspect's house, a van pulls up, obscuring their view. Having missed the briefing, Martella fails to recognise the van's occupants as the armed robbers, and when she approaches their van she is shot and killed. Stamp is wounded, but manages to give a description of the van which is spotted by a traffic police motorcycle. As the India 99 police helicopter and SO19 cars pursue Martella's killers across London, PC Loxton and WPC Ackland disobey Ch. Insp. Cato's orders and pursue the suspect vehicle in the Area Car. The vehicle hits a bulldozer and explodes, killing all inside.