DC Terry Perkins is undercover in prison, where he investigates convicted paedophile Charles Mawdsley who is believed to be running a paedophile ring with the help of one of the prison guards. DS Ramani de Costa appears as a prison counsellor, acting as Terry's contact with the outside world, but when Terry opens up in a group therapy session, Ramani begins to suspect that he was abused as a child. By arresting a corrupt guard who was dealing drugs, Supt Okaro hopes to force Mawdsley to play his hand, but in interview, the guard reveals that the prison's assistant governor is also corrupt. Okaro and de Costa race to the prison just in time to stop Terry from being killed by Mawdsley. Meanwhile DI Neil Manson gets a call from a prisoner at the same nick who wants to pass on information about a huge planned diamond robbery - the grass is none other than Don Beech, Manson's former sergeant at Barton Street and former Sun Hill DS.

DCs Rob Thatcher and Ken Drummond are on an obbo watching a witness in a fraud case, when Ken's son Alex turns up on the doorstep in a state of shock. While on a night out with his mates to celebrate his 17th birthday, Alex believes he has killed a prostitute. Drummond leaves Alex with Thatcher, and rushes to the woman's flat - she is dead, and Ken hastily removes evidence from the scene (Alex's hat). With their obbo blown, and Thatcher suspecting their target has switched places with another person, he and Alex manage to salvage the operation when they find some vital evidence in the target's rubbish bin. When Ken informs Alex of the death, he runs off and is found the next morning threatening to jump off a building, but he is talked down by his father. Drummond replaces the evidence and reluctantly calls in MIT, and Alex is arrested. DI Neil Manson and DS Samantha Nixon discuss DI Cavanaugh's corruption and Don Beech's escape, and they know DCI Jack Meadows will be furious. Meadows a