At the funeral of a suicide victim, Charlotte Moran, her father, Frank Evans, and her husband, Dave Moran are grieving for her. Meanwhile, behind the scenes at the crematorium, John Wheeler also weeps as he prepares Charlotte's coffin for the cremator, when her husband, Dave, angrily confronts him.
Two weeks later, the crematorium secretary, Mary Hunt, reports that both Dave Moran and John Wheeler have gone missing. Rumour has it that John Wheeler and Charlotte Moran were having an affair. DCI Janine Lewis opens an investigation and forensic tests reveal that another body was cremated with Charlotte. But was it Dave Moran or John Wheeler? Janine tells the team they have a murderer and a victim, but which is which?
Richard discovers a match for Dave Moran's metal leg plate amongst the metal remains at the crematorium. So Dave Moran's the victim and John Wheeler's the killer. Wheeler leaves a message for his wife, telling her to meet him in a city square that lunch time. The team lie in wait as a man approaches Mrs Wheeler. When he makes a run for it, they follow and eventually capture him, only to realise he's a petty shoplifter. Janine takes John Wheeler's phone message to a technical expert, who says it is a recording of a recording. So maybe John Wheeler's not alive. Maybe someone just wants the police to think he is.
Janine speculates that they may be dealing with two victims, a different killer and a missing body. If Dave Moran was cremated with Charlotte, what happened to John Wheeler? The team begins to suspect Frank Evans and gain a search warrant for his house and his undertakers premises. They find train bookings suggesting Evans has scarpered and start opening coffins, believing he may be disposing of Wheeler's body in pieces, but to their shock they find the body of Evans himself.
The team question the remaining employees at the crematorium, focusing on Mary Hunt and Roger Boersma. Shap finds some love letters in Roger's bedroom and soon learns that Roger was Charlotte's lover. Richard gets a search warrant for Roger's house, while Janine questions him at work. Butchers discovers that John Wheeler and Charlotte Moran had a baby when Charlotte was only thirteen and that the baby was adopted by a Mr and Mrs Boersma. Without knowing it, Roger was having an affair with his own mother.
To his horror, Richard discovers body parts in Roger's freezer. He's the killer. Trapped with Roger, Janine confronts him. He denies that John Wheeler is his father. He reveals that his father was Frank Evans. Charlotte was abused by her father and the baby was adopted. When they met later they felt drawn to each other and started an affair, having no idea they were related. Roger killed Dave Moran, believing he drove Charlotte to her death. John Wheeler claimed he was responsible and told Charlotte to stop seeing Roger.
Roger killed John too, and only afterwards discovered the awful truth that Frank Evans was the man responsible for all this. Janine tries to get away from Roger, but he knocks her unconscious, Richard and Shap arrive but they can't find Janine anywhere. They learn a coffin has just gone into the cremator. Richard is horrified, but Janine appears – it's not her. Roger must have killed himself. As Janine says: there's some things no-one could live with.