The first episode of this series steps inside the NZSAS's gruelling selection process. Of an initial 50 applicants, from across the New Zealand Defence Force, only those with exceptional physical and mental resilience will make it through the 10-day course. The candidates face a barrage of tests, including timed runs, strength drills, cold-water swims, and heavy-pack marches. Those who fall short are out of the running. To determine who else makes it through, candidates must endure a three-day navigation challenge, including the infamous Exercise Von Tempsky, and a 60 km near-straight-line march carrying more than 35 kgs.