Summary: Film describing the roles and capabilities of the Royal Navy's submarines. The film explains the differences between Vanguard, Trafalgar and Upholder Class submarines and shows the roll-out of HMS Vanguard (S.28) at Barrow-in-Furness. The air, surface and sub-surface threats that may be encountered are illustrated, and life onboard described with scenes of bunks, the galley, NAAFI (small onboard shop), and laundry. The film concludes by listing some reasons why an individual might volunteer for submarine service.