Episode 8

The team faces the job it never wanted: finding Lucas North. Their Section Chief, their friend, one of the best agents MI5 has ever produced, and he has walked away from all of it. Harry decides the team is too close to the target to see straight, so he brings in an outside specialist, Alec White, to run the hunt. Vincent Regan plays White with the brisk professionalism of a man who gets paid to find people and does not care much who they are. Harry has been careful all season about who he trusts, and bringing in a stranger says more about his state of mind than any speech.

Finding Lucas was always going to be hard. Finding a man who has nothing left to lose is another matter, and the episode lets that sink in slowly. The search turns desperate, and what is left of the friendship between Harry and Lucas plays out as a deadly game of cat and mouse across the city. The camera stays close to both men while it happens, and the city does the rest. The episode does not rush the hunt, and it never loses sight of what it is really about. It is the rare hunt where the tracker knows the hunted well enough to predict him and still cannot catch him.

Jonathan Brackley, Sam Vincent and David Wolstencroft wrote it, Edward Hall directed. Peter Firth's Harry carries the emotional weight, Richard Armitage's Lucas the mystery, and Nicola Walker's Ruth, Shazad Latif's Tariq, Sophia Myles's Beth, Max Brown's Dimitri, Simon Russell Beale's Home Secretary, Laila Rouass's Maya, Hi Ching's Yimou and Vincent Regan's Alec White fill the frame around them.

The season has been heading here all along, and the whole team is too close to the target to see it clearly, which is why Harry called in a stranger in the first place. And while the chase itself is taut enough, the real pull is watching Harry try to hunt down a man he helped make.