After seven years in prison for the murder of his wife, David Collins is released due to a technicality. The police now need to reopen the case in search for the murderer.

As DI Hudson's new investigation unearths serious flaws in the original murder investigation, those who were closest to Tara are forced to explain away credible motives for wanting to kill her. Relationships are strained to breaking and damaging accusations fly when David confronts his brother and sister-in-law over access to his children.

Alice and Rob's relationship continues to disintegrate as evidence under questioning incriminates them further, and the children grow closer to David. Meanwhile, Tom's attempts to save his marriage are destroyed by his subsequent arrest, and forensic evidence throws new light on David's original conviction.

David is the subject of a sensational tabloid story, and struggles to explain things to his children. Tom is confronted by his ex-wife, who demands his help. Last in the series.