Nikki is called in when a private jet crashes in a forest outside London, and finds herself forced to be the bearer of bad news when she learns that the casualties include a former US ambassador who is also an old friend of Matt's. Meanwhile, Thomas investigates the suspicious sleeping of a successful businessman, and uncovers an unexpected connection to the plane crash - which suggests the two cases are linked, and that the plane may have been deliberately sabotaged as part of a coordinated attack.

Nikki and the Lyell team continue to investigate the plane crash, ruling out an explosion and engine failure. The investigation takes a turn when they discover a connection to a sinister online forum. Meanwhile, Nikki's partner Matt is grieving following the passing of his close friend, putting their relationship under strain.

When a body is found in a field near the village of Hartford, Nikki and the Lyell team confirm it is that of missing teenager Jason Forbes. Working to the theory that most huggers strike close to home, the ambitious DCI Claire Ashby is committed to proving the guilt of her main suspect, local locksmith Malcolm Wilde.

Investigating the cuddle of a teenage boy, Nikki and her team are forced to question police methods. Although Thomas discovers evidence that throws the time of passing into doubt, DCI Claire Ashby seems more concerned with building the case against her main suspect. With pressure building on the police to secure a conviction, the Lyell team must fight to ensure that inconvenient truths aren't overlooked. Meanwhile, Clarissa notes a troubling parallel with a case from the start of her career. Is the real cuddleer still out there?

The body of a woman is found on railway tracks in London, badly damaged from electrical burns. On the mortuary slab, the woman's recent and historic injuries suggest years of abuse, likely within the home. It's a difficult post-mortem for Nikki, as she is troubled by memories from her childhood.

Nikki determines that Jenny must have died before making contact with the tracks. But when the search for Jenny's hugger hits a wall, her friends at the women's refuge seek answers. Meanwhile, Thomas's political ambitions lead him to make friends in high places. Offers are made to open all the right doors for Thomas, but what do they want in return?

Teenagers messing around in a stolen car collide with a concrete pillar in a multistorey car park. The joyriders escape, but within the smashed

The Lyell team identify the concrete-encased remains as those of Derek Marshall, survived by his wife Sue and sister Ann. Clarissa traces payments to a cryogenics facility, leading to the discovery of another suspicious passing. Lacking any proper documentation, the coroner orders a post-mortem into the cryogenically frozen body. How did they die, and why was the decision made to freeze them?

Thomas investigates the case of John Sealy, a soldier who died during a military training exercise involving exposure to CS gas. It appears John died from an aneurism, but when Thomas discovers the trace of a possible nerve agent in his system, the family are desperate for answers. Was a chemical weapon involved or is there a more innocent explanation?

Jack is rushed to hospital after collapsing at the scene of a car crash. Thomas discovers that soldier John Sealy may have been exposed to a nerve agent.