Halfway through the course, 10 trainees remain. Control must use a series of exercises to decide who they'll take on the course's final overseas challenge: a brutal decision they'll be forced to make shortly. Among the exercises is one of the most notorious in spy training. Control tell the trainees to enter a pub and - with nothing but their own guile and imagination - extract key intelligence from unwitting strangers. Roopi impresses with her natural performance, but Lisa and Hugo almost blow their cover, and serious questions are raised about Rohan. In another exercise Control bring in two former detectives to challenge the trainees' ability to defend their cover, but one of them falls at the first hurdle.
In the concluding episode of the series, six trainees remain on the course but only four of them will make it through to the final test overseas: exercise solo. This final challenge, a mission on foreign soil, has been designed to recreate the conditions for operating as an intelligence officer in a hostile environment. Dispatched to Marrakech, the final four must work entirely alone. Unknown to them, Control are also in the city and watching their every move as they move between locations and are given limited instructions. On arrival they must hand over their passports to an unknown contact before using their alias documentation to check in to a nearby hotel. Control have secretly rigged their hotel rooms with cameras and plan to test the trainees' behaviour as they ratchet up the pressure and suspicion. Battling rising paranoia, the trainees must try to act naturally, but one candidate struggles to maintain their composure.