D.S. Roach is interviewing a suspect, Barron, about a cash and gold bullion robbery. There's not enough evidence to charge him, and Barron knows it. Roach is desperate to find the link, and he asks D.C. Lines to do some unpaid overtime to help him. Lines is reluctant, as his eldest son is ill, but manages to square it with his wife. Roach and Lines visit one of Barron's associates, Halloran, in his nightclub, and Halloran gives them a name of someone who may have laundered the cash for Barron. Finding a laundrette at the address, they realise they've been had. Seeing police outside the house of Barron's ex, Cheryl Maynard, they discover that a neighbour has reported a robbery but Cheryl's saying nothing - it looks like Halloran has taken the money and gold. Roach releases Barron with his apologies, but takes great pleasure in mentioning Cheryl's empty cellar.

D.I. Burnside's unorthodox policing methods, which include flushing an informant's head down a toilet, set him on a collision course with D.C.I. Reid, who has already received several complaints about Sun Hill officers. Reid fears the worst when she is called in to Scotland Yard for an urgent meeting with MS15.

Stamp and Page attend a break at the home of Barton Street PC Steve Bennett, who returns after a night out with Quinnan to find his daughter's bedroom has been vandalised. He enlists the help of Stanton to investigate what Bennett's wife claims has been an ongoing campaign of harassment. Bennett points Quinnan in the direction of an ex-lover, but it proves to be a non-starter. Attention then turns to local villain Dougie Davis, who has history for a similar campaign of harassment against another Barton Street PC, however he is incarcerated. Attention then turns to an unlikely source, but events take a dramatic turn when Bennett is injured in a hit and run. Meanwhile, Jenny has a frosty encounter with uniform at Stamp's birthday party, dampening her relationship with Quinnan.

Webb and Spears investigate when a house fire traps two young girls, who end up in hospital in a critical condition. Meadows is later assigned to lead the investigation when suspicion soon falls on a loan shark who was seen outside the house just before the fire. When witnesses place him elsewhere at the time of the fire, suspicion then falls on the girls' father, however questioning him is delayed when one of his daughters succumbs to her injuries. With Webb convinced of his guilt, Spears clashes with him when she suspects the mother is to blame. After cracking the case, Webb and Spears grow closer.

Accompanied by Hollis, Petrit manages to locate his sister Nicola, who has been working as a prostitute for Berisha. Her colleagues at the brothel rumble them when Petrit refuses to leave his sister, forcing Hollis to blow his cover and call in his colleagues to raid the place. As Quinnan and Page try to save the operation, they find their old passion reviving as they settle into their roles as a husband and wife. Stamp is furious to discover CID have a camera in Quinnan and Page's bedroom, but his shock is compounded by seeing them in a passionate clinch. Quinnan receives a life changing offer, and he stuns Page with a massive offer.

Wayne Radford has been found dead in his prison cell. It appears to be suicide, but Radford also has a number of bruises and cigarette burns on his body. Insp. Gina Gold hears from Radford's cellmate that a copper was spreading rumours that Wayne was a child killer. Malcolm Willard's garden centre has reported him missing, and DS Ramani De Costa is concerned as she suspects DC Terry Perkins has been to see his childhood abuser. PC Reg Hollis and PC Steve Hunter find Willard alive and well at his home, but are called back later to find DC Perkins' brother Ben trying to drown Willard, who is later shot dead. PC Andrea Dunbar is on a crusade to clear Supt Adam Okaro's name, and angers DI Neil Manson when she illegally submits one of Jerome Taylor's cigarette butts for a DNA test, to prove that he planted the marijuana in the Super's car.