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 celebrities take on hand-to-hand combat, then 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, force march and carry a 40kg fuel drum over rough terrain. By the end of all this, some will be heading home.

The celebs engage in hand-to-hand combat against the directing staff, run down a 50-metre pillar and go diving for essential supplies. Meanwhile, one recruit is medically withdrawn.

The last five celebs are put through two gruelling tasks, before being sent on the run for an escape and evasion manhunt. Who has the mental resolve to make it to the end?

The last five recruits are on the run from a specialist hunter force who are trying to track and capture them. If captured, the recruits will face the most psychologically demanding of all the phases, interrogation.