The search is on to find the missing suspect. Linda and Walti revisit an old case in an attempt to gain the upper hand over Waingrow. After weeks of speculation, the events surrounding Angela's murder are finally revealed.

The net closes in around Dr Crowley. Fresh testimony helps the investigation - but reveals a secret from Linda's past.

Lucy reveals a secret past which devastates Bobby, while police in Germany and the UK make a breakthrough involving drug trials.

Now that the Ghost Detective has been unmasked, Alec and Nina trade favours for information, but fail to consider the deadly repercussions of their actions. Bobby and Linda come up against a cunning adversary in Dusseldorf, and a surprise ambush leads to a breakthrough in the case - but leaves lives hanging in the balance.

Bobby arrives in Dusseldorf to uncover the mystery surrounding Ruben Locana's death. Chasing a lead turns out to have catastrophic consequences for one of the detectives on the case.

Alec is rescued from the water and has an unexpected visitor in hospital… Meanwhile, in Dusseldorf, Linda has a breakthrough and she starts to believe that Ruben Locana’s death wasn’t an accident. And it’s a race against time as Bobby, Nina and Alec try to locate the mystery pages at the heart of the case.

As pressure mounts to wrap up the case, the detectives uncover clues of their own that point to the murder being more than just a random attack.

When local GP Angela Benton is murdered in a children’s playground, detectives Bobby Day, Nina Suresh and Alec Wayfield embark on what appears to be a straightforward murder investigation. However, it soon becomes apparent that Angela’s death has more to it than meets the eye.