A man and his dog find a child’s skeleton in an abandoned mine, and a woman, Sylvia Stewart, is attacked in Victoria Park on her way home from work. A Jamaican man, Donald Palmer, is arrested who denies the assault but he knows the victim well. Under questioning in front of her parents she denies knowing a black man and Dawson believes the prejudice of the time prevents her telling the truth. DI Burns sends Dawson to the library to look at newspaper back issues for news items about a missing six year old boy.

Dawson discovers a newspaper item about two missing boys thirty years previously and DI Burns and Dawson break the news to one of the boys mother who identifies effects found with the skeleton as her son William. Chief Superintendent Coulson (revealed as Constable Coulson's father after a station inspection), who was a Sergeant at the time of the boys going missing, arrested a man for their murders and with little evidence and no bodies had the man committed to an asylum where he subsequently killed himself. DI Burns is still searching for a second skeleton. A second woman is attacked in the park but Sergeant Fenton dismisses the victim as she is a known prostitute. Dawson sees this as evidence that the locked up Palmer is innocent and risks her career by going to a West Indian club for information, only for Fenton to find her there.

DI Burns continues his investigation of the missing boys, as William is laid to rest, interviewing another suspect from the time. Fenton is a laughing stock when an informant misleads him about a planned bank robbery location, but he turns it to his advantage when he leads the capture of the gang at their hideout. A third woman is attacked in the park and Dawson goes to Palmer's trial to convince Sylvia Stewart to tell the truth. Fenton is furious with Dawson as the trial verdict is challenged. Burns' marriage is falling apart due to his wife's mental problems. Constable Coulson is stabbed breaking up a fight at a coffee bar where Dawson is present, along with her boyfriend and Desk Sergeant Pratt's son.

All the resources of the station are turned to finding Coulson's attacker, and Fenton and Dawson work together and identify the attacker, Johnny Harris, a friend of Sgt. Pratt's son, who is in hiding. Burns has committed his wife to an asylum and his children are taken by his mother-in-law. Dawson consoles Burns over a drink in a pub overseen by Fenton who spreads malicious gossip throughout the station. The investigation into the missing boys continues and Burns' search uncovers a recently dead woman, who had a child aged six who died thirty years ago, who was living with her son of 37 who does not have a birth certificate. Fenton captures Coulson's attacker with help from Pratt's son. A fourth victim is found in the park - this one is dead.

The dead body in the park is another victim of the assailant, the first to be murdered. The Chief Superintendent - dissatisfied with Burns progress - seconds Sergeant Fenton to the C.I.D. and take charge of the investigation. Under pressure from Chief Inspector Nelson, Fenton decides to use Dawson as a decoy to flush out the assailant which she readily agrees to despite Burns objections. The plan works and Fenton arrests a suspect and in the confusion Dawson is left behind at the mercy of the real assailant and goes missing. Burns detective work and Fenton's doggedness lead a two pronged search for Dawson that takes the case in a full circle.

The travelling fair comes to Brinford and the search for a runaway girl draws WPC Gina Dawson into a feud between the fair workers and a gang of Teddy boys. Back at the station she struggles to remain professional when Jack makes a shock announcement. Meanwhile, Fenton clashes with the new DI when a dead body is discovered but is there more to the mystery than either of them realise?