Senior Forensic Chemist PO KWOK TUNG (Wayne Lai) is the head of the Forensic Department and is skilled at analyzing criminal psychology. He has an unique view on human nature, familiar with the structure of various firearms. TUNG works closely with Senior Coroner CHUNG HOK SUM (Maggie Cheung) in a wide range of fields including psychology, anthropology, criminology and forensic science.
OCTB Senior Inspector LIN SIN YEE (Kate Tsui) and Chief Sergeant MOK CHAN TUNG (Ron Ng) work together cracking many murder cases. Their relationship goes from good friends 'brothers' to a pair of lovers.
With a backbone of 12 cases, the forensic scientists, forensic doctors and the police all work together to accommodate each other to solve these cases. The perspective in this third installment is much wider than the previous two seasons with a legal standpoint in addition to the forensics.