Sam comes under intense scrutiny during an official inquiry into the deaths of two brothers while they were in prison. Her findings are soon challenged by her colleague, Leo Dalton, who is brought in to perform a second autopsy. Meanwhile, a series of murders that are taking place cast suspicion on a recently released ex-convict. He served years in prison after being convicted of killing his wife; the evidence against him was given by Sam during one of her very first cases. During his time in prison, however, he continued to deny his guilt. Sam begins to believe that someone is stalking her, while the police have trouble locating the ex-convict.

Sam and Leo, colleague Pathologists, are on opposing sides of a high-profile court case.

The body of young Colin Connor is found in an attic at a former hospital now marked for residential development. He had been stealing metal but was locked in the attic by his accomplice who then fled. The culprit seems to be Derren Blackburn whose father lies for him when D.I. Cherry visits with Jack. At the same time, Leo is asked by distraught father Tom Hancock to conduct a post mortem on his son Peter, who, Tom is convinced, died because of electrical towers outside his window. Leo is surprised to find that Peter and Colin had an identical kind of kidney dysfunction. James Embleton, a government minister who begins dating Nikki, is in charge of the hospital conversion, and is visited by the sinister David Loader, who warns him of Leo's investigation into Colin's death. Leo and Jack look for proof of toxicity at a farm near the hospital, but are evicted by the army. Leo contacts George Ryder, who owned the farm, and they agree to meet at the hospital as George has an important revelation, but tragedy intervenes.

After Darren is killed trying to escape, his father tells Leo of the boy's recent personality change, and examination of his body shows he had Fanconi's Syndrome like Colin and Peter. Nikki tells James that Leo suspects a conspiracy, especially after George's daughter has spoken of the haste with which the family was moved from the farm and the poor compensation they received. James now comes to see that his father, Sir William, and his henchman Loader - who Jack proves killed George Ryder - are involved in a cover up. After being falsely discredited and suspended from work, Leo joins Tom to investigate the woods near the farm and hospital and discover what the cover up had been trying to hide. As Nikki asks James how much he knew, Tom sets out for revenge.