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.

The pressure mounts on the detectives to wrap up the case. However, Bobby, Nina and Alec uncover clues of their own that point to the murder being more than just a random attack. The detectives chase a lead that results in devastating consequences for one of our detectives.

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.

Identification of the ghost detective proves difficult when Michael's interference forces the elusive investigator underground, forcing Nina and Alec to rethink their approach. Bobby arrives in Dusseldorf to uncover the mystery surrounding Ruben Locana's death. And chasing a lead turns out to have catastrophic consequences for one of our detectives...

With the ghost detective's identity revealed, Alec and Nina find themselves trading favours for information which soon has deadly repercussions... Meanwhile, Bobby and Linda come up against a cunning adversary in Dusseldorf. And a surprise ambush in a hospital leads to a breakthrough in the case but lives hang in the balance.

Bobby is close to breaking point as the detectives in Dusseldorf continue to be the target of Waingrow's taunts. Alec makes a significant discovery in the case that links Dr. Crowley to Rustin Wade. Meanwhile, Lucy reveals a secret past that devastates Bobby.