In Season 1, a serial killer preys on men, Carol tries to catch a stalker plaguing a celebrity couple and an abduction and murder cause professional tension between Tony and Don.
In Season 2, Tony persuades the police to reopen the case of a convicted child-killer, building work unearths grisly remains and an imprisoned gangster masterminds a murder.
In Season 3, a boy's body is discovered in a warehouse, one of Tony's PhD students is suspected of murder and Carol contends with a sniper spreading terror throughout Bradfield.
In Season 4, Carol is replaced by new detective Alex Fielding, a prostitute is murdered and Tony investigates a series of deaths resembling the martyrdoms of Christian saints.
In Season 5, Tony is called in to help investigate the abduction of an 11-year-old girl and the murder of two youngsters in ritual slayings leads the team to investigate black magic.
Robson Green and Simone Lahbib return for the sixth series of episodes adapted from the novels by Val McDermid. Dr Tony Hill (Green) is a clinical psychologist who is called into another ongoing case by ambitious DI Alex Fielding (Lahbib). The episodes are: 'Prayer of the Bone', 'Unnatural Vices: Part 1', 'Unnatural Vices: Part 2', 'Falls the Shadow: Part 1', 'Falls the Shadow: Part 2', 'From the Defeated: Part 1', 'From the Defeated: Part 2', 'The Dead Land: Part 1' and 'The Dead Land: Part 2'.