Episode 5

A wealthy couple are taken hostage, and the kidnapping of Jessica Carrodus turns out to be only the start. Luther and the team chase the people behind the abduction through a case that keeps changing shape, with diamonds at the centre of it and the Carrodus family's money making every lead harder to trust.

The search pulls in a string of people circling the family: Tom Meyer, Daniel Sugarman and Evangeline Nixon, each with their own reasons for being near the Carroduses and their own version of events. Thomas Lockyer's James Carrodus and Donatienne Dupont's Jessica give the case its human centre, while the team works the angles around them. The episode was written by Neil Cross and directed by Stefan Schwartz, and it gives the regulars a properly busy hour. Steven Mackintosh's Ian Reed and Warren Brown's Justin Ripley do the chasing, Saskia Reeves's Rose Teller keeps order, and Zoe Luther's own life keeps running in parallel, a reminder that Luther's world does not stop when he is looking elsewhere.

And the personal thread is the one that lands. What starts as a hostage case turns out to be about betrayal inside the family, and Luther is close enough to it to feel the shape of it in his own marriage. The show does not spell the parallel out, which is the right call. It just lets the two stories sit next to each other.

The diamonds matter less than the reasons people took them. By the end of the hour the case is resolved in the way these cases usually are, with bodies counted and the survivors left to carry it. Luther walks away with the professional box ticked and the personal one still open.

That is the episode's quiet trick. The violence is loud, but the wound it leaves is not in the chest of any of the dead.