Shadowplay (2)

The question hanging over Shadowplay (2) is simple and awful: is The Shepherd a real man, or a symptom? Boyd and the team keep working the arson case and the other crimes connected to it, hunting for an identity that may not exist outside the imagination of a mentally ill woman. Either answer is bad. One means a killer walked away; the other means a confession sent them chasing a ghost.

Part two adds a fourth young woman. She has schizophrenia, and The Shepherd gets inside her paranoia with what can only be called expertise, feeding it until it points somewhere useful to him: at psychiatrist Matt Carney, brother of her own doctor David Carney. A vulnerable mind steered towards murder, using her illness as both weapon and camouflage. It is a cruel piece of plotting, because every warning sign she gives off reads as symptoms rather than cries for help.

The Carney brothers give the danger a human centre. When your own patient is aimed at your own brother, medicine stops being a safe distance from the crime.

Barbara Machin and Ed Whitmore wrote it, Andy Hay directed, airing on 16 August 2004. Trevor Eve leads as Boyd with Claire Goose as Silver and Wil Johnson as Spencer. Sue Johnston's Grace Foley and Holly Aird's Frankie Wharton hold down the psychological end, alongside Paul Kaye as Dr David Carney, James Larkin as Matt Carney, Lucy Gaskell as Fay Harding, Laurence Penry-Jones as Adam Duke and Hannah Barrie as Emily Dell.

What the episode does well is keep the detectives honest about how little they know. Their evidence comes from witnesses whose minds they cannot fully trust, so every step forward carries doubt in it.

The Shepherd turns out to be exactly the kind of predator this show does best: ordinary, plausible, and hiding behind someone else's diagnosis.