When local GP Angela Benton is murdered by an oddly behaving man, detectives Bobby Day, Nina Suresh and Alec Wayfield commence what appears to be a straightforward investigation - but there is more to her death than meets the eye.

Pressure begins to mount on the team to wrap up the investigation, but they uncover clues suggesting the GP's murder was not a random attack. Chasing a lead turns out to have serious consequences for one of the detectives.

Alec is rescued but in hospital he receives an unexpected visitor. In Germany, Linda has a breakthrough and suspects that Ruben's death was no accident. In England, the team race to locate the pages at the heart of the case.

Bobby arrives in Dusseldorf to join the German investigation of the murder of Ruben Locana. Attempts to identify the Ghost Detective are hindered by Chief Inspector Michael whose interference drives the elusive figure underground.

Waingrow's taunts bring Bobby close to breaking point and things get worse when Lucy reveals a secret past. Meanwhile, the German and British teams make a breakthrough involving drug trials.

Dr Crowley is arrested but continues to protest his innocence, while the net closes in around Waingrow - but the police are not the only ones gathering evidence against him. Fresh testimony aids the investigation but reveals a secret.