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

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 must abseil 200 feet off a dam and climb a mountain in blistering heat with 40lbs on their backs

The recruits work in pairs as they tackle the threat of chemical warfare and execute a fast-paced extraction in near-freezing water. Then, it's time for brutal hand-to-hand combat.

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.

The recruits race each other across sand dunes in the Sahara and must cross a valley at night while avoiding hunter teams who are tracking them with dogs

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

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 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

21 new recruits embark upon a recreation of the brutal SAS selection process, starting with an ambush, a hijack and a 100-foot abseil, which proves to be the toughest course to date.

The remaining men and women's final challenge is also the most psychologically demanding: resistance to interrogation, as they're subjected to stress positions, white noise and relentless grilling.

The recruits face a forward abseil and an arduous beasting by the DS. There's also an extreme water immersion exercise and a team event in a dark network of disused tunnels.

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 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 recruits' will to survive is severely tested with an extraction task used in the Vietnam War. Then the recruits must make it through a survival task that requires navigating through the jungle while being pursued by hunters.

In the Vietnamese jungle, the group are tasked with a 200-foot abseil into a dark bat-infested cave. In a bustling market, the recruits must take down an armed gunman in a crowd of civilians. And then they take on each other in a game of murderball.

The remaining 11 recruits face a hostage rescue mission hoping to spring two abducted recruits. The second challenge is a punishing head-to-head team ammunition supply race in the jungle.

After a beasting on base, the teams are pushed to their physical limits as they race to pull vehicles weighing 1000kg from the sand while under indirect simulated fire. Calls from home unsettle some and prompt an honest reflection of the cost of war.

The seven remaining recruits are ambushed by a hunter force team behind enemy lines. Handed over to interrogators for questioning, the recruits must endure psychological and physical punishments designed to break their will and force a confession.

The recruits take part in extreme hand-to-hand combat. A breach of camp discipline leads to a 'beasting'. And a recruit gets stranded up a huge waterfall.

A new elite training team welcome 20 brave recruits to the searing, epic Jordanian desert, with an intense start crossing a ravine balancing on a rope suspended 165 feet above the ground, and escaping a room full of CS gas.

After a set of tasks designed to test trust, including hand-to-hand combat and a terrifying abseil, Shylla's pushed to confront how a lifetime of racism has made her withdraw.

In the series finale, the last recruits are subjected to all kinds of punishing interrogation techniques. In the most feared phase of the course, they receive severe punishments, being buried alive, and thrown in water tanks, to force a confession.

The recruits try a seven-metre backwards dive and face an elimination sickener on a major sand dune. After hand-to-hand combat in murderball, they're ambushed while driving back.

Twenty recruits prepare to enter `Jungle Hell', the toughest phase of SAS selection. First they are tasked with traversing the 'trainasium', suspended 50 feet above the ground. Then they must complete a 200-foot abseil headlong into a waterfall.

The recruits are stalked across the Scottish Highlands by a military-trained hunter force, before facing extreme interrogation on limited sleep and rations. Who will crack?

The recruits' grit is tested as Jay's undercover status is revealed and he launches a brutal beasting to expose the weakest in the group.

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.