A police officer is killed while responding to a domestic disturbance call. When DCI Alan Banks is called to investigate the grisly scene, he discovers it's the home of a serial rapist and murderer.

DCI Banks and Annie Cabbot investigate a murder on a canal boat destroyed in a fire and evidence quickly points to the victim being involved in an art forgery scam. But with a second body discovered, confusion mounts as to who was the intended victim.

Cabbot investigates when a woman is found murdered on the moors. Her name is Lucy Payne, and within a short time there's a number of suspects. Meanwhile, Banks is called in when the body of a teenage girl is discovered in a storage room. The detective and his team find themselves investigating the murder of one of their own.

[Season Finale] The detective is drawn into the criminal underworld of Soho when he reluctantly accepts an unofficial request from Chief Superintendent Rydell to find his missing daughter. Meanwhile, an armed robbery in Eastvale turns into a murder investigation after the perpetrator is found dead in his home.

Banks' very own brother is under suspicion for murder.

While Banks searches for his missing younger brother Roy, DI Helen Morton has become convinced that Roy is the prime suspect in the Jennifer Lewis murder.