Episode 3

Luther's feelings for Jenny have grown into something he acts on, which for him means trying to protect her and help her stand on her own feet. Baba is having none of it. The woman keeps him on a tight leash, and the episode opens with that standoff already in place, two people circling each other over one vulnerable girl.

Then the job comes calling. A man is committing brutal murders in public, escalating each time, and there is no motive in sight. Luther is used to killers with reasons, however twisted. This one appears to kill for nothing, and the absence of meaning makes the case harder than any clue could. A killer with no reason cannot be reasoned with, and the team is slow to admit that. Jenny is left alone and exposed while the investigation eats his attention. But the episode lets that loneliness sit rather than rushing to fix it.

Neil Cross wrote the script and Sam Miller directed. The cast is deep this week: Nikki Amuka-Bird's Erin Gray and Warren Brown's Ripley work the case with Luther, Babou Ceesay's Baba glowers from the edges of his life, Golda Rosheuvel's Sally Thomas and James Puddephatt's Steve Kimble fill out the station, and David Dawson's Toby Kent adds a note of unease that pays off later. Steven Robertson plays both Robert and Nicholas Millberry, a detail the show does not underline but which fits its habit of doubling people.

The mystery of the unmotivated killer is the spine, and it holds. Every clue feels heavier than it should because nobody can say what it means, and Luther is reduced to reading tea leaves and hating it.

The episode ends with the case open and Jenny further from safety than she was at the start. The quiet anxiety of the last scene stays with you.