The NLF want to make a trade. Alison watches over Ed, feeling conflicted about their marriage. Yusra smuggles a coded message to Armstrong and Joe decides to go against his orders.

Cast: Essie Davis, Jessica Raine, Jessie Buckley, Stephen Campbell Moore, Ben Miles, Jeremy Neumark Jones, Tom Glynn-Carney, Ouidad Elma, Chris Reilly, Amanda Drew, Louis Greatorex, Richard Dillane, Mark Tandy, Kal Naga, Stuart Graham