Celebrities undertake a series of extreme tasks, including jumping backward out of a helicopter and hand-to-and combat, as they begin the challenge of completing the gruelling SAS selection course.

Recruits confront their fears head on with a 60m high forward abseil; a rough game of murderball on a black mud plain leaves a recruit with a near concussion.

In an abandoned abattoir, recruits face a life or death decision before they are drilled physically into the early hours of the morning.

The recruits must wait to be rescued by their teammates in freezing waters; the contestants take on a test of pure grunt and teamwork; one recruit makes a surprising departure.

The recruits must crawl across a jagged ravine on one rope above the ocean; the contestants get submerged in cold surf; the recruits experience a physical drilling that puts them on the brink of physical collapse.

The fatigued recruits are dropped from a helicopter into four-degree water while carrying 20kg backpacks. They must make their way to the shore as a group, before racing to the top of a mountain.