A man accused of opening fire on a crowd from a multi storey car park, and killed a policeman, is claiming his innocence. Boyd's colleagues question his loyalties when he seems unwilling to re-investigate. As DC Mel Silver digs deeper, she discovers some disturbing truths about her boss.

Boyd struggles with his past while continuing the investigation on a mass murderer who was also guilty of killing his close friend. Are the Gunman's claims of innocence true? As the team investigate it looks as if someone else may have been involved.

When a convicted killer is cleared at appeal for the murder of his adoptive father ten years previously, Boyd is not convinced that the man is innocent. But the only way to find out is to track down the rest of the family - and with a big inheritance at stake, both parties appear to have a lot to hide..

Following the murder of Mark Lovell's cousin, the team establish that Mark has a watertight alibi, and the search for the real murderer narrows down to the remaining family members.

Their investigation into the two remaining family members is further complicated by the discovery of drug dealing and involvement in the witness protection scheme.

A recovered memory therapist alerts the CCS to a care home regime of sexual abuse of young boys and a suspected murder. Her client who revealed all this in a therapy session goes missing and the team strongly suspect he has gone on the hunt for the man who abused him and murdered his friend.

ln their attempts to prevent another murder, the team desperately tries to establish the identity of the care home paedophile who is also being hunted down by two of his victims..

A mummified body sends the Cold Case Squad back to the sixties and to a Notting Hill house which had been featured in a film as the location for a murderous fight between gangsters.

Renovation works at the house in the present day reveal more bodies behind the walls.

The film starts to appear not so fictional after all. Things get even more complicated when Spencer tells Boyd that he and his family lived there when the events took place.

The gangster responsible for the bodies behind the walls in the Notting Hill house is still active and the unearthing of past events provokes more murders and an international turf war.

Spencer's family history is the key to unravelling the mystery.

In 1948, post-war Britain, an ex-soldier has been found dead with his skull nailed to the floor. Now this case has been re-opened due to media attention and pressure created by his grandson.

Is the Second World War the linking factor? The team must find the next possible victim but no-one knows where he is.

As a garage is demolished in contemporary London, demolition work is halted at the sight of a skeleton sitting in the driver’s seat. An unexploded bomb is found under the car which is soon linked to an Irish terrorist cell from the late 1970s.

While the security services begin using underhand methods, a former army officer promises Boyd explosive new evidence—but their meeting is destined never to happen.

Two five-year-old twins are taken from their home in Notting Hill Carnival and a nationwide search is launched, but they are not found. Thirteen years later, one of the twins, Jason, is admitted to hospital after a traffic accident. The hunt now begins to establish where his sister, Cindy might be and if she is still alive.

After shooting an unarmed man in the raid on the nursery, Mel is suspended from the case pending an inquiry. Grace and Boyd, meanwhile, have more questions for Roper—but the doctor's in no position to answer them.

After Sam is released from prison, a man is murdered in the hostel where he stays. Soon he is a suspect. But it looks as though Sam was in fact the intended victim. On the surface Sam appears to be a devoted family man, but he has a hidden past which the team can only speculate about.

When the gun stolen from Frankie is used in another murder, the Squad suspect the victim's gopher. It is revealed the first murder could have been a case of mistaken identity. Frankie and Grace begin to get creeped out by the effects of Boyd's Anger Management!

A sadomasochistic serial killer is at large. The killings are brutal and the victims are found with the word 'Sorry' carved in their backs.

When the killer strikes at the heart of the team, the investigation takes a new track and the motive for the murders takes on a very different meaning.

A young woman who has psychiatric problems has killed her family through an arson attack on her family home. She claims she was incited to do this by a mysterious figure known only as 'The Shepherd'.

Boyd and the team continue to investigate the arson case and the other two other possible crime connections to 'The Shepherd'. Will the team discover this person's true identity or will it all turn out to be a part of the imagination of a mentally ill woman?