Episode 5

An American president is in London, officially on his first state visit and actually here to chair top secret peace talks between Israel and Palestine. Beth Bailey and Dimitri Levendis go undercover as Home Office representatives, with the small, thankless job of keeping the delegates apart until the talking can start. It is the kind of diplomatic chore that usually makes for a slow hour. Then someone works out how to kill the president, and the hotel goes into lockdown. The whole episode is the answer to one question: who is locked in with whom.

The show has the good sense to stay inside that single building once the alarm sounds. The lockdown turns the hotel into a holding pen for every faction at the table, and Beth and Dimitri have to move through it without blowing their cover while trying to find the assailant. They are the only ones who know the talks are even happening, which makes every polite conversation with a delegate feel like a bomb waiting to go off. The tension is the old locked-room kind, and it works. There is something quietly horrible about a peace conference becoming a trap, and the script does not cheapen it.

Jonathan Brackley, Oliver Brown and Sam Vincent wrote it, Julian Holmes directed. Peter Firth's Harry, Richard Armitage's Lucas North and Nicola Walker's Ruth Evershed hold the Grid end, with Sophia Myles's Beth and Max Brown's Dimitri carrying the field. Simon Russell Beale is the Home Secretary, Iain Glen's Vaughan Edwards hovers in the background, and Laila Rouass's Maya Lahan and Mounir Margoum's Muatt Hutri fill out the edges.

The plot is a familiar one, and the show knows it. The pleasure here is watching two agents do a diplomatic job with a gun in the room. And the ending, when it comes, belongs to the people stuck in the middle of a peace nobody quite trusts. It is not a flashy hour, but it is a properly tense one.