Six weeks into their training, the marine recruits face their first pass-or-fail test. They must complete a tough series of physical challenges in the gym, culminating in three staggeringly high rope climbs. If they fail to complete it they'll have to leave their troop.

The troop 174 recruits reach the challenging halfway point in training. The second half of the course includes more challenging exercises to prepare the recruits for frontline fighting, but this is traditionally a point when many recruits leave the troop, either through failure or giving up.

As training progresses, more and more recruits start to struggle with the tough demands placed upon them.

The raw recruits take the next step on their training and there are challenging new lessons at every turn. If they can make it through the next three weeks, their families will get invited down to witness their progress and they'll get to go home for the first time since training began.

As training progresses, exercises start to imitate life at war, and the nature of the job begins to worry some of the recruits of Troop 174.

As the recruits reach the end of training, thoughts turn to life beyond Lympstone. A familiar face, Corporal `Froggy' Chauffour, returns to prepare the troop for a final pass-out parade, and four contenders compete for the coveted King's Badge award, which the winner will carry with them throughout their career. Meanwhile, retiring Troop Commander `Ginge' Booth contemplates a future beyond the Royal Marines after 28 years of service.

This first episode follows 56 new recruits through this so-called 'shock of capture'. The recruits spend these opening weeks living in a 60-bed dorm where their every waking hour is controlled by their drill instructor, Corporal 'Froggy' Chauffour.

The recruits are within touching distance of their green berets, but first they must face Lympstone's ultimate challenge - the famous commando tests - four gruelling physical exercises attempted over five consecutive days. The members of 169 troop are a tight-knit group who have pushed through 30 weeks of training together. They're desperate to finish the course as one, but not everybody will make it