Summary: When the pathologists investigate three suspicious deaths in one night on the same ward, it looks like hospital staff may be behind their murders. Nikki becomes increasingly disturbed by a rape and murder case involving a young child.

Summary: Nikki's mental instability worsens, and Harry and Leo are forced to get her psychiatric help. But then when the true identity of the murderer is discovered, it becomes a race against time to save Nikki's life.

Summary: Leo finds himself haunted by past memories when he returns to Sheffield after an ancient body is unearthed on Bleaklow Moor.

Summary: Leo investigates a potential copycat killing, but the team are starting to wonder if Karl Bentley was wrongly convicted, leaving the real murderer free to set out on a new killing spree.

Summary: As Nikki investigates the drowning of a young mother, Harry is called to an apparent suicide at a nearby army base; it soon starts to look like the cases may be linked.

Summary: Having established that Lieutenant Lockford was murdered, Leo makes a startling breakthrough, and the investigation begins to unmask a dark secret at Hillsdon Army Base.

Summary: When human rights lawyer Anna Sandor calls Harry to Budapest to investigate the death of a client, they start to uncover a sinister underworld conspiracy, putting both their lives in danger.

Summary: With Harry dead and Leo and Nikki getting nowhere with the police, the pathologists struggle to clear Harry's name, while the police seem intent on covering up a wider conspiracy.

Summary: After a major incident at the Dutch Embassy, Harry and Nikki are removed from the case when the Dutch decide to appoint their own pathologist.

Summary: When the Van Burens' au pair commits suicide, the pathologists start to unravel the truth behind the embassy shootings, and a dark family secret is exposed.