Nikki becomes even more involved with the Ndrangheta mafia-group and Jack uncovers some disturbing leads. An unlikely alliance leads Nikki closer to the truth, but not without some collateral damage.

Harry and Nikki make a crucial connection between the dead girls and sex-grooming victim Shannon, but is it too late for Hannah and Lauren?

A woman's body is found on railway tracks in London. When the post-mortem reveals signs of domestic violence, it brings back troubling memories for Nikki.

When the team's search for Jenny's killer hits a wall, her friends at the women's refuge seek answers. Meanwhile, Thomas makes some friends in high places.

When a man plummets from a high-rise building, the Lyell team cross paths with the NCA and a notorious mafia group, pushing Nikki to make a tough decision.

The investigation continues to take unexpected turns, with Nikki managing to get behind the mask of the lead suspect. Jack has a breakthrough at the festival site and Nikki takes a dangerous opportunity. A surprise event at the Lyell brings some hope.

The Lyell team work together to find out why the lorry was found with bodies inside and a dead driver at the wheel, and are truly shocked to discover where it leads them. Gabriel becomes emotionally invested and is presented with an ethical dilemma, and Jack gets a surprise visit.

Nikki stumbles across a sinister underworld where teenage girls are groomed for sex and forced into prostitution.

The Lyell team return to the tunnel and uncover some difficult truths, while the police raid the protester camp, desperate for answers. Family ties are pushed to their limits.

A lorry is found with people locked inside, some dead. With the survivors refusing to speak, Nikki and the team must use their pathological and forensic skills to identify them.

The Lyell team are thrown into the dark side of social media, where nothing is as it seems, and the perfect profiles of the influencers they are investigating raise disturbing questions. As a heavily pregnant DI asks the team for their expertise, are they running out of time to solve this case?

Stranded in the flooded care home, Jack and Simone fight to keep the residents alive - but Nikki discovers that they may be trapped inside with the killer.

Jack, Nikki and Simone investigate another death connected to the underground boxing ring. Jack's loyalty is tested when he fears Ryan has put Cara in danger.

Nikki’s students make an alarming discovery while dissecting a body donated for their training. Jack and Simone try to save care home residents from a flood.

Levelling-up leaders and environmental activists clash in a small town trying to look to the future. With a sabotaged train and a dead mayor, the activists become suspects.

With Nikki missing, Harry works against the clock to find out who is responsible for the murders and finds himself in a cover-up.

When the mutilated body of a young boy is pulled from the river, Leo is determined to give him an identity and to bring his killers to justice.

Leo refuses to back down in his search for the killers of the young boy, despite threats and increasing racial tension.

When a Zimbabwean asylum seeker is unfairly deported to South Africa, Leo needs to find a way to help her return to the UK.

Nikki is forced to make some hard choices when she discovers that Anton has been less than honest with her.

Human remains found on an Afghan water supply project send Leo, Nikki and Jack to the war-torn region to establish if it is a missing British soldier.

The murder of a promising boxer draws Nikki and Jack into the world of underground boxing. Meanwhile, Jack's brother Ryan is released from prison.

When a woman confesses to murdering her husband, the Lyell team must determine if all is as it seems. Meanwhile, Simone is shocked to be reunited with a detective from her childhood and struggles to untangle her past.

Harry and Nikki are drawn into a war between a medical research establishment and a group determined to take direct action.

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.