In this dramatic first episode, Julia Bradbury climbs aboard the newest, biggest and most powerful ship in the fleet: the aircraft carrier HMS Prince of Wales. The ship is leading the biggest exercise since the cold war, and Julia gets a taste of what life is like on board for its 1400 crew.

The Prince of Wales' is home to eight F-35 jets, and Julia gets first-hand experience of just how powerful they are on the flight deck – one of the most dangerous places to work anywhere in the world – as they take off from just metres away from her. From launching jets to chopping veg, Julia also heads below decks to the galley where she discovers what's involved in cooking a Sunday roast for nearly a thousand hungry sailors.

Former Royal Marine JJ Chalmers heads back to his old stomping ground, the Marine Commando Training Centre in Devon, where ordinary civilians are turned into elite commandos. It's been 18 years since he completed his training and earned the coveted green beret, but not much has changed as he follows a group of new recruits being pushed to the limit.

JJ then heads to Portsmouth to discover more about a controversial moment in the navy's recent history. The last time an enemy ship was torpedoed and sunk by a British vessel was during the Falklands Conflict, when submarine HMS Conqueror engaged the Argentinian Light Cruiser, the General Belgrano. JJ meets a veteran from the submarine's crew who was on board at the time, to hear first-hand what happened beneath the waves of the icy south Atlantic.

Also in Portsmouth, Julia dons her Navy uniform again – but this time she's handed a rifle and razor-sharp bayonet too. She's learning drill marching, an essential skill to build discipline amongst raw naval recruits. Can Julia keep in-step with the recruits and, more importantly, keep the training instructors happy?

Finally, JJ visits a naval institution that cements the royal link to the navy: Dartmouth's Britannia Royal Naval College. It's on its croquet lawns that royal romances flourished, and is the place where both King Charles and Prince William completed their officer training before both leaving their mark on the ceiling of the grand wardroom.