Will Brutus Stab MI5 in the Back? - S0.E450

The problem with some Double Agents is that it’s very hard to trust them. After the mercurial Polish pilot and spymaster Roman Czerniawski offers his service to the Allies, MI5 and Double Cross worry that their new man will turn out to be a Triple Agent! But they’ll have to learn to trust agent Brutus because he might just hold the key to success in Operation Fortitude.