Julia Bradbury and JJ Chalmers are given unprecedented access to the Royal Navy. Julia boards aircraft carrier HMS Prince of Wales, and former JJ returns to Marine Training Centre.

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.