Episode 1

Luther comes back to work still carrying the death of his ex-wife, and the show wastes no time handing him something to match the mood. A masked murderer is at large, a man who appears to be trying to write himself into folklore, and the killings have a dreamlike quality that makes them harder to read than plain violence. The body count climbs while Luther works out what the mask means. Folk tales need a monster, and this killer is composing himself as one.

He is doing two jobs at once. The folklore killer needs stopping, and at the same time an old acquaintance's daughter needs pulling out of the dangerous world she has fallen into. The two cases do not connect, which is rather the point. Luther is being asked to save strangers and people he cares about in the same week, and the episode keeps both plates spinning without dropping either. And neither rescue can wait. Luther knows it better than anyone.

Neil Cross wrote it and Sam Miller directed. The cast around Idris Elba is a proper ensemble this time: Ruth Wilson's Alice Morgan, Dermot Crowley's DSU Martin Schenk, Nikki Amuka-Bird's DS Erin Gray, Warren Brown's Justin Ripley and Lee Ingleby's Cameron Pell all get their moments, with Michael Smiley's Benny Silver, Paul McGann's Mark North, Kierston Wareing's Caroline Jones and Anna Brewster's Abby filling out the edges.

The folklore angle is handled with a straight face, which is the right choice. A killer who believes he is becoming a legend is more frightening than one who is merely insane, because he has an audience in his own head. Luther reads that, and the episode lets him.

It ends with the mask still on and the case unfinished, which suits a season opener. The night is not over for anyone.