Actors Maisie Smith and Jennifer Ellison, entrepreneur Calum Best, Olympic medallist Fatima Whitbread, reality TV stars Pete Wicks and Ferne McCann, ex-footballer Ashley Cain, influencer Amber Gill, dancers AJ Pand Curtis Pritchard, Olympic sprinter Dwain Chambers, taekwondo Olympic gold medallist Jade Jones, boxer Shannon Courtenay, and Paralympic high jumper Jonathan Broom-Edwards take part in a special edition of the training challenge. In the first episode, the recruits must crawl through sand in blistering 40-degree heat, before facing every desert soldier's worst nightmare - a gas attack.

Twelve celebrity recruits remain from the original 14. Entering the next phase, the celebs face a series of tasks that will test their resilience to the max. In teams led by the fiercely competitive brothers Curtis and AJ Pritchard, they take on the gruelling task of moving a broken-down one-tonne Jeep to a safety zone over half a kilometre away - in searing heat and through thick sand. After being banned from athletics for using performance-enhancing drugs, ex-sprinter Dwain Chambers is eager to impress the DS as the celebrity recruits are tasked with balancing on ropes 160ft above the ground to cross a ravine.