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.

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.

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

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

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.