Spies

The trainees go through two training exercises: Surveillance and Alias. In the middle of a busy south London market, the trainees are tasked to follow a target covertly.

In the Lethal Force exercise, the group are taken to an undisclosed location in the countryside and asked to work out the right course of action when there are no clear options.

Halfway through the course, ten trainees remain. Control must use a series of exercises to decide who they'll take on the course's final overseas challenge. Among the exercises is one of the most notorious in spy training.

The final challenge for the six remaining trainees has been designed to recreated the conditions for operating as an intelligence officer in a hostile environment. Dispatched to Marrakech, the final four must work entirely alone.