Carl Meyer (Jonathan Slinger) has been released from prison on parole after serving 20 years for the murder of 14-year-old Jane Crewes, who went missing along with her best friend Harriet Collingham. Meyer was also the chief suspect for Harriet’s murder, but as her body was never found, he couldn’t be charged for the crime. Frost (David Jason) is perturbed by the news of Meyer’s release. He worked on the case 20 years ago and is desperate to know where Harriet’s body is buried, not only for the family’s peace of mind, but also for his own.

Elsewhere, as some female members of the divorce support group, Motivation Plus, owned by Roman Cassell (Dhafer L’Abidine) and Tom Brody (Vincent Leigh), enjoy a drink in the local pub, it’s clear they have a plan. Later that night, one of the women, Susan Hepworth (Amner Agar), meets Cassell and gets into his car, while her friend, Katie (Sarah-Jayne Steed), gets into Brody’s car. Katie and Susan lure the men to a nearby lake and persuade them to go for a late night skinny dip. Unbeknownst to them, the women run off with their clothes as the two men find each other in the lake and realise they’ve been set up.

Back at Motivation Plus, a van pulls up driven by Jason Cohu (Ariyon Bakare) who works as a handy man in the building. He is with an older man, Joshua Ray (Joseph Marcell), who keeps watch as Jason breaks into the building and hacks into Cassell’s computer.

At the lake, Brody and Cassell scramble around trying to find clothes and are forced to steal items from a clothes line in a nearby house. As they run across the road closely followed by two police officers, they’re almost run over by an amused Frost, who takes Brody to the station while Cassell escapes to the Motivation Plus offices. He discovers Cohu sitting at his desk and as the two men fight, Ray hears what’s going on and heads towards the office.

The following morning, the receptionist at Motivation Plus arrives to find Cassell’s dead body lying in a pool of blood. Frost and Toolan (John Lyons) arrive to survey the scene of the crime and it becomes clear that they have a murder investigation on their hands – Cassell was hit across the head before falling down the stairs. It also becomes apparent that the victim is the business partner to the streaker who was arrested last night.

Elsewhere, Meyer is finding it increasingly difficult living in the same village as the victim’s families and everyone is making him feel very unwelcome. Meanwhile, David Crewes (Keith Barron), whose daughter Jane was murdered by Meyer, is at church with his sister Gloria (Paula Wilcox) and her husband Charlie (John Castle), their daughter’s body was never found. Meyer join the service but as he quietly prays at the back of the church the congregation become aware of his presence. David and Charlie make to leave but Gloria stops and pleads with Meyer to tell her where her daughter’s body is. Meyer tries to free himself from her grip but when Gloria falls to the floor, Charlie punches him.

Back at the police station, a nervous Joshua Ray has turned himself in for the murder of Roman Cassell. He claims he went back to Motivation Plus after the scuffle with Cohu to try and reason with him, but lost his temper and killed him. However, Frost isn’t sure that the evidence proves either men are to blame for the murder.

On a nearby housing development, a man operating a bulldozer discovers a human skull. Frost is called to the scene and is convinced it belongs to Harriet Collingham. His opinion is confirmed when Harriet’s locket is also found on the scene. The case against Meyer is officially reopened, he has denied both murders for 20 years and was never tried for Harriet’s murder as a body was never found. Faced with new evidence Frost reckons he’ll have no choice but to confess. However, as Harriet’s remains are examined some unexpected results are uncovered which complicate the case. Frost is forced to re-examine the evidence, will he be able to solve the crime so long after it was committed?

Sunday, 12 October 2008, 9:00PM – 11:00PM, ITV1