The team are called to the hospital where an enraged Dr. Mellor is having treatment after being attacked by an assailant carrying a lethal syringe full of drugs. Mellor is adamant that the man responsible is one of his colleagues Dr. Finn. When word comes from the hospital that Mellor has discharged himself, DCI Burke (Alex Norton) and DS Reid (Blythe Duff) go to his house to talk to him. When they get there he's dead... The team step up the investigation to hunt for the killer, but their skills are pushed to the limit when a macabre discovery sends them in a completely different direction.