Burnside arrests a man on suspicion of robbery with violence. Tosh and Carver get given wrong addresses. Burnside's suspect is identified in an id parade but she tells Jim his snout told her the suspect is guilty. It turns out he is not guilty of robbery with violence but his mum brings in her vacuum cleaner with drugs in the bottom. Reg chases a mother who tried to buy a watch with a stolen credit card and recognises her as a habitual criminal.

Tosh is at the building society waiting for an armed robber. Dave and Barry assist CID and they catch an old age pensioner. Steve goes to a disturbance behind a pub. He finds an attacked man. He thinks it might be racially motivated. It turns out to be a revenge attack.

Called to attend to a pub brawl, PC Tony Stamp and PC Dave Quinnan are stunned to find one man unconscious and the other Sun Hill's own DS Ted Roach. Roach is taken back to the station, and while DI Frank Burnside manages to pursuade the victim to drop the charges against him, nothing can be done when Roach headbutts Insp. Andrew Monroe during a heated argument. Ch. Supt. Brownlow calls in MS15 to investigate him, but Roach turns in his warrant card and walks out of the station.

George is chasing a suspect but loses him. Steve searches the area and spots him. When caught he has just dropped some LSD tabs. The suspect tries to do a deal with the D.I. about getting bail to attend his brother's wedding. Regional Crime Squad:Drugs are in the station and organising a raid on the factory. Meadows gets upset because of a missing witness and Meadows wants the D.I. to go and talk to the witness. The D.I. wants to be in on the drug raid. Haines talks to the very scared witness. Haines is head hunted back to the drug squad. Meadows is not happy when told by Brownlow.

WPC Ackland and PC Loxton are on foot patrol when they are approached by a Mrs Henry with a minor complaint. A shot rings out, hitting Mrs Henry and SO19 are quickly on the scene to evacuate the officers and the wounded woman. CID, including WDS Jo Morgan who has been seconded to Sun Hill as a liaison to the Regional Crime Squad, can find no reason why the woman would be the target of a sniper. PC Loxton, who is testifying in a court case later in the day is assumed to be the target and is given SO1 protection, although subsequent raids of the suspect's property put him in the clear. That night however, as Loxton slumbers in a safe house, someone firebombs June Ackland's flat.

As it becomes clear that someone wants June Ackland dead, she is horrified to find CID digging through her painful past to discover the killer's identity. Tired of being holed up in a safe house, Ackland decides to go back on duty, as this may also draw the killer out of hiding. There is a close shave when she is seperated from Sgt Cryer on street patrol and a man pulls an imitation gun on her, although she is rescued by a covert SO1 officer. Meanwhile, a witness to the arson on Ackland's flat, Mrs Cooper, comes into the station to make a statement.

The identity of the man trying to kill June Ackland may be revealed when an ex-Army officer is overheard boasting that he was paid to ""kill a copper"". CID link him to a young man who committed suicide in prison after Ackland arrested him for dealing drugs on the Jasmine Allen. WDS Jo Morgan realises that their witness, Mrs Cooper, is behind the plan as she turns out to be the mother of the dead boy. Mrs Cooper is arrested for conspiracy to murder, and she reveals that the assassin is lying in wait for Ackland at the safe house. As Ackland and an SO1 team head off to the safe house to draw the killer out, they are ambushed by a man on a motorbike just outside the station, and Jo Morgan is killed in a hail of gunfire as she rushes to warn them.

Santini is first on the scene of a serious car accident, and becomes a bit of a local hero when he bravely dives into the river to secure the car, which is teetering on the edge. However, the driver reveals to him that upon his possession he has a bag of cocaine, a present for his mistress. He asks Santini to destroy it if he doesn't make it. Santini manages to take possession of the bag when he recovers his personal affairs at the mortuary, but when Stamp and Garfield inadvertently discover Santini's misgivings, it's not long before they realise that their fellow officer may be playing for the other side. Harker is on the fence when Santini gives him a cock and bull story about the situation.