16 celebrity recruits are pushed to their limit in the unforgiving Vietnamese jungle. The new recruits must first traverse parallel metal bars suspended 50 feet above the ground. Then they must fight against each other in the rawest form of combat.

The celebs face a punishing search operation through a series of rooms filled with CS gas. And they're tested under pressure during a rescue mission when they're tasked with extracting two of their fellow recruits who've been taken hostage.

The celebs first climb up a 200-foot cave, and abseil back down again. The second task is murderball: a serious test of physical strength and aggression. Finally, the recruits must write a 'death letter' to their loved ones.

Twelve celebs remain deep in the punishing environment of the Vietnamese jungle. Their trust in each other and themselves is tested in a task so gruelling that they start dropping like flies.

The remaining eight celebrities must pull themselves across a 300-foot-wide ravine, before dropping 160 feet to the extraction point. Then to weed out the weakest recruits, the celebs take a midnight beasting, and make an emotional call home.

For the penultimate phase of the course it's survival of the fittest during a bout of pontoon wrestling. The remaining recruits are then ordered to head off into the jungle on a risky mission behind enemy lines.

For the series finale, the five remaining celebrities endure intense interrogation. The interrogators subject the exhausted and hungry recruits to punishing techniques as they attempt to unpick their cover story and reveal their true mission.