From the recruits' very first challenge - a terrifying backwards dive out of a helicopter - Ant Middleton and his team are determined to show there will be no allowances made. Later, the celebrities have to overcome more fears.
Chief instructor Ant Middleton and his directing staff put the celebrity recruits through a series of tests. One celebrity recruit collapses on a mountain and another is badly affected by the extreme cold, as they face brutal challenges.
The celebrities are paired up to prove that they're team players, and must put their lives in each other's hands, in a terrifying free fall abseil. They must leave their celebrity world behind and learn to trust their partner to keep their place.
As the pressure is piled on, one recruit cracks and a bad decision puts another's place on the course in dire jeopardy. After being pursued through the Chilean countryside by a military hunter force, the recruits enter the interrogation phase.
The remaining celebrity recruits face a final, brutal challenge at the El Morado glacier, 3000 metres above sea level. A dozen celebrities started, but only a few have what it takes to complete the course.
The recruits face a terrifying 50-metre free-fall off a cliff, followed by boxing with a twist. Katie Price must cope with the pressures of past and present. Tony Bellew battles with his inner demons.
In the second selection phase, the celebs face murderball, a brutal beasting, a backwards helicopter dive into near-freezing waters, and a few home truths. But who will make it through?
The celebs are put in specially selected pairs. They must eat, sleep and operate as a duo. Joey Essex and paralympian Lauren Steadman may shine as individual players, but can they do teamwork?
The recruits face a killer 48 hours primed to expose the weakest members - including a beach beasting in near-freezing water and a gruelling race across mountainous terrain.
The remaining celebs face a punishing race across land and ocean before they plunge into an overnight pursuit by an elite hunter force across the Scottish Inner Hebrides.
The final six celebs go through 48 hours of torture enduring the interrogation phase. Only the physically and mentally elite will make it to the end.
Twelve celebrities head out for the wilds of the Scottish Hebrides for a series of full-on challenges in a gruelling version of the SAS selection, including an aerial assault course.
The 12 celebs take on hand-to-hand combat. They also put their wits to the test in a hostage rescue mission. With tension mounting, two of the recruits are soon heading home.
The celebs do pair work as they descend 100 feet down a rock face, go on a tough march, then carry a 40kg fuel drum over rough terrain. By the end of all this, some will be heading home.
An intense start for the recruits - crawling through sand in 40 degrees.
The celebrity recruits face a series of trust exercises, including jumping from a helicopter in pairs before working together to get to shore. However, when some of the group lose equipment and fail to keep their kit dry, all the recruits are punished for the mistake. Jennifer Ellison and Ferne McCann have to overcome their trust issues and self-doubt to freefall from a 150-foot cliff
The recruits take on the gruelling task of moving a broken-down one-tonne Jeep in searing heat and through thick sand. Then the celebs must balance on ropes 160 feet above the ground to cross a ravine.
Shannon Courtenay comes face-to-face with her anger issues, and Ferne McCann confronts her fear of the dark when the recruits are forced to dive backwards from a seven-metre platform into the waters of the Gulf of Aqaba in the dead of night. At the end of the episode, the DS drop two recruits from the training program.
Chief instructor Rudy Reyes puts Ashley Cain and Maisie Smith to the test, challenging them to get all their equipment across a body of water by zipline, without it getting wet. Finally, back in the blistering heat of the Jordanian desert, two teams of recruits must work out how to load and pull a 200kg sled loaded with equipment up a narrow ravine
The celebrities face the penultimate survival phase of the course, where they prepare for life on the run behind enemy lines. An ambush triggers traumatic memories for AJ Pritchard. Messages from home threaten to unsettle the recruits ahead of the escape and evasion phase, while Calum Best leads his team astray as they try to avoid capture by a relentless Hunter Force
The last seven celebs face the final brutal phase with a punishing interrogation with ice baths and burial to force a confession. Will they crack or make it through to the end?
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.
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.
Fifteen celebrities are about to be pushed to the limit in the spectacular but unforgiving landscape of New Zealand's South Island, starting with an intense rescue mission.
The celebs tackle terrifying feats to test their discipline, including a forward abseil down a 300-foot working dam and an alarming backwards dive in the dark.
The celebs are paired with an 'oppo' for mutual support as they pull heavy equipment across treacherous, icy mountain terrain. But then they have to fight each other.
The remaining celeb recruits face the ultimate test of nerve in their most terrifying ordeal yet: an escape from a simulated helicopter crash in near-freezing water.
In a test of their control, the celebs must protect a VIP on a journey through the wilderness. But one recruit has already been pushed to their limit.
It's time to test the already exhausted remaining recruits' survival instincts. After a plunge in freezing mountain water, will they have anything left to confront the Redman?
It's time for some true grit from the recruits - moving equipment over treacherous terrain, an ambush followed by dead-of-night escape, evasion... and mud wrestling.
In the series finale, the remaining celebs are ambushed behind enemy lines and handed to expert interrogators for the ultimate psychological and physical challenge.
