Silent Witness - Season 21

Haunted by her experiences in Mexico, Nikki Alexander is struggling to come to terms with life back home.

Whilst on leave she seeks out fellow pathologist Sally Vaughan (Emma Fielding) for support. However, a few days later and troubled by the failure of Sally to return her calls, Nikki heads to her house only to find that it has become a crime scene and Sally is nowhere to be found.

Nikki's suspicions over David Cannon are further aroused when she discovers blood in the boot of his car. With Thomas' support she takes samples to test for DNA. Does it belong to Sally Vaughn?

Nikki and Jack deal with their feelings post Mexico in very different ways.

Jack is boxing with his sparring partner, DCI Naomi Silva when he is called to a crime scene.

While Nikki is busy examining the body of a young woman Karen Sawyers, Jack is surprised to find the SIO on the case is Naomi Silva.

The first prime suspect, Karen's husband Pete, is found covered in blood and clearly suffering. The forensic evidence leads the team to a cosmetic clinic, where a pregnant Karen had been receiving various treatments seemingly free of charge.

Nikki and Silva soon become frustrated when Simon Laing, the CEO of Hamilton Ashe hospital, blocks their access to Karen's medical records. However, when a second body is found and all evidence leads back to Hamilton Ashe, Laing is forced to help the team.

Meanwhile, when Thomas's daughter Rosie unexpectedly turns up at the Lyell, Thomas has to deal with a more complex role... being a father.

Nikki comes face to face with CEO Simon Laing when it becomes apparent that the motive for the murders may have been blackmail.

When the team find that the hospital computer database has been hacked, Clarissa and Max follow the forensic clues to a teenage hacker called Splinter.

However the danger grows much closer to home when Nikki receives a threatening text with a picture of Thomas's daughter Rosie.

A US diplomat is shot dead in a central London square, forcing the team to work closely with the embassy and the FBI and to overcome jurisdictional hurdles.

Nikki is still in shock as the team arrive at Matt's residence but insists on working at the Lyell, determined to help. When analysing crime scene photos and the positions of the victims' bodies, Nikki realises there is a pattern. Together, the team uncover a secret that has been held by those at the very top of the US government.

While two care home staff are chasing Kevin McDowd, a young man with learning disabilities and sociopathic tendencies, Nikki and Jack examine a fatal road accident where the deceased is Kevin McDowd's mother. The investigation led by police sergeant Button should be straightforward, but the forensic evidence suggests foul play.

The team are determined to uncover the truth about unexplained deaths of patients at a care home. They are desperate to rescue Serena and return her to safety. Unbeknownst to her colleagues in the Lyell Centre, Clarissa allows herself to be admitted to the care home in order to investigate. Her determination to find out what happened leads her to uncover a shocking truth, but puts her life in danger.

It is Christmas morning and Nikki is awaiting a call from Matt who is back in the States. Instead, she receives a call to say that the team is needed: a family has been massacred at an enormous property owned by Andy McMorris, the CEO of a haulage company.

Greeted by SIO DI Gibbs, Nikki is first on the scene whilst Clarissa is connected to the action via screens and microphones back at the Lyell. Having left his father to celebrate Christmas without him, Jack is just arriving to join them when a gunshot suddenly rings out.

With Gibbs lying on the floor with a life-threatening injury, the team realise that the shooter might still be on the grounds. Are they also in danger?

As the truth behind the McMorris family is revealed, the team is brought together by the conclusion of a shocking Christmas family tragedy. Reuniting with their respective families, Nikki finds her secret Santa gift is a visit from a loved one.