Episode 2

Beth Bailey's first undercover job for MI5 is to guard a man she barely knows. Robert Westhouse is an oil baron with a target on his back, and the intel says an assassination attempt will come at a meeting of top oil dealers, which is a roomful of reasons to be nervous. The ambush arrives anyway, off schedule and messy, and suddenly Beth is in the middle of something that looks like her old life, the mercenary one she left behind. The ambush puts both the baron and Beth's cover in the same crosshairs.

The episode is as much about whether Beth can stay inside the story she is telling as about who is shooting at Westhouse. And while that fire burns, Lucas goes to visit someone who never expected to see him again, and the hour lets that thread sit quietly until it matters. The episode keeps it vague, which is the right call.

David Farr wrote it, Michael Caton-Jones directed, and it aired on 27 September 2010. Sophia Myles gets the meat of the hour as Beth, with Richard Armitage's Lucas running his own errand. Peter Firth's Harry, Nicola Walker's Ruth, Shazad Latif's Tariq and Max Brown's Dimitri Levendis hold the centre, while Simon Russell Beale's Home Secretary, Iain Glen's Vaughan Edwards, Laila Rouass's Maya Lahan and Richard Jacobs's Hotel Receptionist complete the bill.

First assignments are a staple of the genre, and the show has the sense to give Beth one that actually frightens her. The ambush does the obvious damage; the past does the rest. It is a quiet episode in parts, and all the more tense for it. Beth is still finding her feet in the show, and this hour does the finding for her. It is the sort of debut that makes you glad she is staying.