JJ Chalmers heads to HMS Raleigh in Cornwall, the home of Royal Navy training, to see how recruits are prepared for the harsh realities of war. Kate Humble is aboard a warship as a brand-new helicopter pilot takes an important step in their career - landing on the deck of a moving warship at sea for the very first time. Also, JJ explores the legacy of HMS Ark Royal, one of the Navy's most iconic aircraft carriers.

JJ Chalmers joins marine recruits under fire training in the Devon woods, Julia Bradbury gets to steer the HMS Prince of Wales, and Rob Bell is on one of the UK's nuclear subs.

JJ is put to the ultimate Marine training test, and also remotely drives an attack boat. Julia visits HMS Belfast to talk to veterans about what naval life was like during WWII.

Kate Humble enters the secret and clandestine world of submarines. She is invited to step on board a British nuclear powered attack submarine at the secretive base of Faslane in Scotland. Former Royal Marine JJ Chalmers heads back to his old stomping ground, the Royal Marine Commando Training Centre in Devon where his training began 18 years ago.

Kate Humble joins British Warship HMS Dragon and the crew of over 200 off the coast of Norway as the ship prepares for its next big mission. She witnesses them testing their weapons to confirm that the ship and crew are ready for battle. JJ Chalmers is invited to join the Royal Marines Band Service for a very special performance at Manchester's Bridgewater Hall.

JJ Chalmers heads to the unforgiving terrain of Dartmoor to push himself to the limit to find out whether he still has what it takes to match the standards of a Royal Marine. Kate Humble is granted behind-the-scenes access aboard HMS Iron Duke - a frontline British warship with 200 crew on a mission to safeguard the nation's shores.