Season 15 - Episode Guide

When Leo's friend commits suicide, Harry and Nikki are called to the scene of a violent and calculated murder, which is thought to be the work of an apparently dormant serial killer.

Harry and DI James deviate from the original investigation to secretly test DNA evidence from the rival Chesham laboratory to try to solve this stalled case.

Harry is disturbed to be called to a crime scene at the home of a family he knows, and finds the bodies of the mother and her teenage daughter, while her stepson lies in a coma - although her toddler has been left unharmed. The police suspect the woman's husband to be the killer - but the pathologist is not so sure of his guilt. The double-murder investigation reveals more about the tangled lives of the inhabitants of Magnolia Drive

Harry and Nikki delve deeper into the tangled lives of the inhabitants of Magnolia Drive.

Nikki is approached to help identify the paltry remains of a serial killer's undiscovered victims.

Nikki is forced to confront manipulative serial killer Arnold Mears face-to-face in order to save Annie.

Leo battles with the authorities at the notorious Redhill prison to seek justice for the murder of an ex-prison inspector.

While Harry and Nikki investigate DI Bridges, Leo puts himself in danger when he follows his instincts and trails violent prison officer Kessler.

Leo is determined to uncover the truth surrounding the mysterious death of a young girl who was being treated by his college friend Delaney.

Nikki and Harry track down the Catholic nun behind the exorcism, only to find that John now believes he's possessed - but can he be saved?

Nikki stumbles across a sinister underworld where teenage girls are groomed for sex and forced into prostitution.

Harry and Nikki make a crucial connection between the dead girls and sex-grooming victim Shannon, but is it too late for Hannah and Lauren?