The team is called out to Northern Ireland to investigate the bodies of two men killed by paramilitaries twenty years ago. For Sam, it is a case that is soon to turn personal.

As Sam struggles to find reconciliation with her estranged son, the investigation takes a darker turn as she has to face up to the possibility that her father may have been involved in police corruption and even murder.

Tensions are running high in the 'leaderless' team as Leo and Harry clash over an investigation into an outbreak of breathing difficulties among children on the South Coast.

While Leo fights for his job, he and Harry investigate an apparent case of Munchausens by proxy and race against the clock to prevent a potentially fatal environmental disaster.

Harry is called out to a death at a racecourse. A jockey was killed when his horse pulled up and fell, crushing him to death.

The police and Harry find that a group of doctors are in a syndicate that owns race horses. One is a kidney Specialist and another is a Plastic Surgeon with a gambling problem. A young woman is going to pay for a kidney transplant privately as the National Health Service wait list is long. She and her husband wish to have a baby after that. There is a helicopter accident and it all becomes a complicated story to figure out for the team of Pathologists who have a temporary visitor called Nicki who is borrowing the lab to obtain a narrative about an Iron Age family whose bones she has to examine. Written by Chris Williams

The team investigates the derailment of a train caused by someone leaving Maj. Mark Wiltshire's Land Rover on the tracks. The army is suspected but Wiltshire was in the officers mess at the time. The team have yet to identify the 21st victim, or determine if that person was on the train or in the car. Working with a survivor's group, they try to re-create where everyone was seated just prior to the crash occurring. When of the survivors commits suicide, the crash claims its 22nd victim. Written by garykmcd

The investigation continues and one of the survivors remembers a vital piece of information. It becomes evident that the identification of body 21 may also lead to the cause of the crash. In the end, the solution rests on discovering a an unknown romantic affair and marital betrayal. Written by garykmcd