William Gaminara

The case of two young women shot dead in a house basement forces Jack to lock horns with an old flame, the ambitious DI Chrissy Reed. As the pair's animosity rapidly escalates due to their conflicting motive theories and failure to ID the victims, Nikki's probing unearths the potentially career-damaging truth behind it.

Nikki, Jack and Leo struggle to identify the human remains with only sections of skeleton found and basic forensic facilities. As they put the pieces together and assemble the skull fragments, they make an unnerving discovery that challenges their theory of what happened to Dan Lambert.

As the basement women case highlights two cooperating killers, Nikki, Jack and DI Reed realize one victim was killed by a controlled sedative, stolen from a high-tech vaccine research lab. And suspicion falls on Lucas Ballinger, a scientist who works there.

Whilst Nikki and Jack close the net on Brian Blackburn's troubled son for murdering his co-worker at the eco-housing project, Leo finally finds someone willing to confirm his fear about the mysterious local health hazard. But when his would-be-informant is found murdered, Leo is convinced he was the victim of a government conspiracy to conceal the truth.

Whilst Nikki, Leo and Jack struggle to ascertain how Deanna was killed and ended up in the Thames, DI Gold focuses on two main suspects in John Briggs' inner circle. However, when Geraldine makes a sinister confession about why she gave her daughter up for adoption and disowned her wealthy family, it dramatically changes the course of the investigation.

Leo races to find a connection between two apparently motiveless murders as a third killing takes place at a school and the police decide they are looking for a serial killer. Nikki, meanwhile, proves that her elderly victim did not die as a result of being attacked.

Nikki's investigation takes an unexpected turn when she reaches January House Care Centre and finds that Morrie has tried to commit suicide.

The search for Liam resumes. Nikki's loyalty towards her former mentor, Noel Hopkins, is severely tested when past allegations of sexual misconduct from a former student surfaces. Leo and Harry refuse to give up their search for Liam, as they try to identify and locate a toxic chemical, which was found in both bodies. If they can find the source of the chemical, they may find where Liam is being held.

Leo investigates a drunk who died on a night bus, Nikki investigates the poisoning of a go-ahead sales executive, and when Harry is called out to the apparent suicide of a premier league football star he uncovers a link back to the accident at the housing estate.

Harry is called to investigate the death of Dawn Pivcevic, who seemingly drowned in a paddling pool containing three inches of water.