Phase two begins with chief instructor Billy determined to understand his celebrity recruits inside out. With psychological insight from Dr Gareth and a rare glimpse into Billy's own past, the recruits quickly learn what's expected of them. They're thrown into a life-or-death combat scenario as they're forced to decide in a heartbeat whether to fire or hold their nerve. Then a terrifying 230-metre crawl through mud-filled tunnels pushes fears to breaking point. A brutal beasting follows - and one recruit hands back their armband.

A brutal race up 27 flights to the top of a dam pushes the recruits hard, after which they must rappel 45 metres back down the dam before free-falling into turbulent water. They must then swim 40 metres to safety in under three minutes. Back at base, nerves shatter and more recruits exit. A high-stakes rescue in a war-torn village tests the remainder's moral courage.