Silent Witness

DCI Jane De Freitas's personal fallout with boss and partner chief superintendent Robert Drake is the least of her worries when three people are shot dead in a petrol station. Nikki and Jack conclude that it is the work of a concealed shooter from long range. A sniper is at large in London. They combine ballistics and wound pathology, along with DCI De Freitas's expertise in victim and killer profiling, to narrow down the suspects. De Freitas contains her undercurrent of animosity towards Drake, as the team work to find the killer apparently striking at random.

The sniper plays a macabre game of cat and mouse with police, while Jack forms a friendship with the teenage son of one of the victims, offering sympathy and support. Thomas tries to ensure the safety of his daughter Rosie and estranged wife Julia amidst growing public fear, while fighting his urge to interfere in their lives.

Nikki and Jack look closer at the targets to elucidate the hidden motive of the killer. The investigation is scaled up by DCI Jane De Freitas, but it's Jack's shocking discovery at one of the victims' homes that leads the team to the perpetrator.

Nikki and Jack investigate a man run down and killed by a tube train. When a female vicar is then murdered after being followed on the underground, the team face the difficult prospect of building a case against her distraught husband.

Nikki forms a bond with high-flying DI Luke Nelson, impressed by his intelligence and compassion. He asks her to help re-evaluate the details of his father's murder when he was a child.

When a young roofer is stalked and brutally killed on his journey home, Nelson and the Lyell team identify a suspect on the tube cameras who links the murders, and a full-scale manhunt is launched.

Tension on the tube network threatens to boil over, and security is stepped up. The accidental verdict in the first death is called into question and the witnesses are brought in for interview. Amongst them is Lana Sutherland, a young hotel worker who has taken in a homeless man, Owen. DI Nelson lets Lana slip through the net before he realises she may be harbouring a dangerous killer.

Nikki helps Nelson unearth the mystery of his father's death, allowing him to confront and resolve the childhood memories that haunt him. He refocuses on the case and, with Jack and Nikki, discovers the missing key that links the victims.

When suspected paedophile Dale Barge is found murdered in a children's playground, Nikki and Jack are brought in by inexperienced detective Rory Drennan. It's not long before the team link Barge's death to a missing child, Lizzie Craddock.

Jack teams up with hard-nosed child protection DI Gina Conroy. They put pressure on Lizzie's parents Johnnie and Cheryl to try to find her. Lizzie's social worker Louise is brought in to help, and Nikki encourages her to stay positive when she blames herself for Lizzie's disappearance.

Daniel Garvey is found dead in his car. Social worker Louise fears that he may have been killed by his 16-year-old stepson Kevin, who has just come out of care.

Nikki, Jack and Thomas focus in on Lizzie Craddock's movements on the night of Barge's murder. Jack and DI Gina Conroy discover Lizzie's last known location but fear what they may find there.

Louise comes under further pressure when she is forced to make a call on whether a sick child, Ricky Mansfield, is being abused by his parents.

A shootout at a City hotel leaves young Ukrainian nanny Sofia Teplov dead, along with an unknown hitman. The Russian oligarch target Maksim Bazhanov narrowly escapes. Nikki and Jack work with young City DI Sarah Parks to ascertain the identity of the dead hitman and find out who is trying to kill Bazhanov and why.

Jack is drawn to Sarah, impressed by her ability to juggle work and family when he finds out her daughter has a rare childhood cancer. The discovery of the hitmen's identities as ex-army frustrates the team when they realise they could have been hired by any number of paymasters.

A young woman working for the Doshi property moguls, Amy Greenwood, is found dead in Maksim Bazhanov's apartment. Maksim is discovered to have been in a relationship with Yasmin Doshi. Nikki, Jack and Thomas ingeniously prove that foul play was involved in Amy's death and help the police find the missing Bazhanov.

Amy's mother Justine is a powerful player in the City Assembly and, fuelled by the death of her daughter, she puts pressure on DI Sarah Parks's investigation. Suspicion soon falls on Adam Lansley of FreeLondon, a violent activist known to target the super-rich. But Maksim is a powerful man with many enemies, and the team find one of them where they least expect it.

Rising star of the police, Sergeant Sam Honeywell, is found beaten and shot in his burnt-out car in Essex. The police are up in arms in what is a hugely emotive and political case for them, and DCI Jim Sullivan is determined to nail Honeywell's killer. But when local drug dealer and son of known crime boss Dean Fallon seems to have his alibi sewn up, suspicion shifts closer to home. Honeywell is discovered to have been in an affair with Kate Parry, wife of his best friend, Sergeant Carl Parry. It looks bad for Parry, and Jack reveals details of Honeywell's final moments, which hits Sullivan hard - he had been like a father to the murdered cop.

Known Essex criminal Jason Simons is found murdered in too similar a way to Honeywell to be a coincidence - beaten, shot and dumped. But as anomalies in his post mortem start to stack up, it is discovered that Simons was not what he seems.

The team find traces of drugs on Simons's penknife that point to a major importation, but his bereaved girlfriend Tess does not seem to know anything about it. Suspicion turns back to Dean Fallon, but a discovery in his medical records and the death of the Fallon family lawyer, Ben Osrin, takes the investigation in an unexpected new direction.