Harry Cunningham investigates when a car accident reveals two bodies inside one coffin. The coffin contained the body of 80-year-old Ethel Mortimer, who was supposed to be there and also that of James Featherton, a high tech sales rep who also had a heavy cocaine habit. Leo Dalton and Nikki Alexander have to deal with the death of a young child who died post-operatively. The pediatric surgeon in the case, Alice Huston, is well known in her field but may be prone to undertaking aggressive surgeries. The pathologists find a connection between the two cases when Featherton's girlfriend is found to be a nurse on Huston's surgical team.

With Claire Kowalski missing and Nikki Alexander unconscious from a blow to the head, Harry and Leo investigate exactly what is going on at the hospital. Harry discovers that a member of Huston's surgical team is not who they claim to be and has actually stolen the identity of someone who died six years before. Blackmail is at the center of it all and it turns out Alice Huston is hiding a secret. However, the killer is identified only by looking to old friendships and the calling in of an old debt.

On Christmas day the team is called to the home of haulage company owner Andy McMorris to find three corpses and Andy disappeared. Sniper shots ring out, wounding DI Gibbs and McMorris's blooded daughter Mel tells Nikki her father shot at her and her horse. A large number of weapons are found in the home suggesting illegal gun importation whilst the diary of Mel's sister Stevie expresses hatred for her father and his estranged wife Zoe. DCI Cooke, a friend of the family assumes the case but appears to be hiding something and Clarissa discovers that the 999 call reporting the shots was made over twenty miles away.

As the three corpses are identified Vernon Rye, a friend of Andy's father Martin, one of the victims, is pulled in after admitting to a fight with him but Mel, recovering in hospital, tells Zoe and Nikki she heard Andy and Martin rowing before shots rang out. Zoe's sister Jackie is another suspect having had an affair with Andy, but claims she left the house before the murders. The discovery of a missing lorry full of guns and another body proves Andy's criminal activities and reveals who made the phone call. Cooke thinks he has found the killer but the pathologists' evidence proves otherwise.