The recruits are forced to master their emotions under extreme pressure - from a scary backwards dive at night to an illusion jump. And, to their shock, the mole in their midst is revealed.

The recruits go on the run across the rugged landscapes of the Inner Hebrides in a challenge designed to test their ability to evade and escape from a pursuing enemy. With limited rations and little sleep, the recruits find themselves ground down in a process where only the strongest will be able to keep going.