The recruits' first task is an unexpected one: writing an essay about themselves. Then they face an eight-mile combat fitness test while their essays are dissected for an insight into their character.

The remaining recruits must choose their weakest colleagues, who then lead the next exercise. And there's the 'Sickener': a series of physical challenges that won't end until five recruits give up.

The directing staff test the remaining recruits' resistance to fear, with mind games and an intimidating challenge to dive backwards from a cliff into the freezing sea 12 metres below.

The directing staff have to whittle the group down to the six they think may have what it takes to complete the final stage: a punishing 72-hour cat-and-mouse chase across challenging terrain.

The remaining recruits each face the final, notoriously gruelling stage of selection alone: 24 hours of interrogation. Do any of them have what it takes to succeed in the Special Forces?

The recruits face a terrifying bridge leap before they can find their base. The jungle environment, altitude and insects take their toll, and the DS give special attention to two volatile individuals.

Chief Instructor Ant and his elite team test whether the remaining recruits can control their aggression, with a brutal game of murderball and the fearsome non-stop 'sickener' exercises

The remaining recruits' trustworthiness is tested, as the directing staff sow distrust among them and ask them to identify their least trustworthy teammates, before a forward abseil trust exercise

The directing staff apply pressure to the last eight recruits, exposing hidden personality traits before sending them into a gruelling 12-hour jungle mission high in the Andes

In the final episode, the remaining recruits undergo the most psychologically demanding 24 hours of the course: the resistance to interrogation phase, as they are abducted and intensively interrogated