In this gritty BBC series adapted from Val McDermid's novels, clinical psychiatrist Tony Hill (Robson Green) puts his psyche's dark side to work tracking serial killers. This season finds Hill clashing with Alex Fielding (Simone Lahbib), an antagonistic new detective inspector with a low opinion of Hill's abilities. Later, a student leads Hill to a death cult, and a recently released prisoner embarks on another murder spree.