As Ben goes missing, Boyd and his team try to force the truth out of a confused David. Boyd grows increasingly close to Sarah, and Stella travels to Poland to investigate the true story.

Boyd receives an anonymous package in the post – a Nazi ceremonial dagger. Attached to it is a Cold Case number, linking it to the unsolved murder of a young girl in May 1945. It seems that Mel had been working on the case before her death, what does this mean for the Cold Case Team?

When they do some digging into the man's past, they discover the deceased was not who he claimed to be, but in fact he had a hidden agenda of his own.

Boyd and the team decide to reopen the 25 year old case of Annie Keel, a woman who was tried and convicted of a double homicide solely based upon her own confession. Boyd doubts the validity of the conviction, and decides to dig deeper to possibly discover what really happened. Why did Annie confess? Did she really commit murder, or was she covering for someone else?

Boyd and the team continue their investigation of the Annie Kee case, and try to locate her son who was present during the murders.

When the corpse of a well-known police woman who went missing a year earlier is found floating in the Thames, Boyd and his team of investigators try to track down who murdered her and her unborn child.

Grace is not convinced that the stalker who confessed to the murder is truly guilty. But who really killed the police officer? Was it possibly the stalker, her ex-husband, or the married father of her unborn baby?

The postliminary inquiries into Harry Newman's past and the identities of the possible twelve murder victims uncover a connection to the infamous trial and execution of a well known gangster.

Boyd and his team struggle to find the truth behind the murder of a prominent Home Office adviser, when a petty criminal is acquitted of the crime. Once a prominent feminist activist, victim Katherine Reed had attacked the establishment at every opportunity, only to later switch sides. Boyd's progress on the case is hampered not only by a Home Office audit, which means the team will be shadowed throughout, but also by the fact that the original investigation was conducted by one of his old flames.

Twelve years after Joanna Gold famously disappeared in broad daylight on Hampstead Heath, the dress she was wearing is found in a lock-up. The team begin the hunt for her killer.

While under pressure to discover the truth behind the murder of young Joanna, DCI Boyd (Trevor Eve) slips up and makes possibly some irreversible mistakes. Joanna's killer begins stalking her sister.

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?

Under the impression that he may receive a confession, Boyd accepts the invite for a visit to the prison from former police officer Eddie Vine, who is serving a life sentence for murdering his friend and former fellow officer, Tom Pallisser.

Boyd is suspended from work after being involved in a hit and run accident while possibly under the influence. While also trying to find out who framed Boyd, the team continue trying to find out if Vine is innocent or not.