Film showing the variety of roles in the Royal Navy by illustrating four seamen, each working in a specific type of ship.

Tony is a crew member on a British nuclear submarine, "a most remarkable vessel". As an artificer (naval engineer), Tony has an important role to play in watching and repairing the equipment. Life off-duty is glimpsed: watching a film ("Up Pompeii" with Frankie Howerd), sleeping in a cramped bunk. Next, we are introduced to 23-year old Alan, a marine engineer onboard a destroyer. Shot of a missile being fired at a remotely-piloted aircraft introduces brief description of destroyer role and of Alan's job fixing all manner of machinery. Opportunity for recreation shown - crew play cards, hockey, go swimming - and travel is highlighted, in this case Turkey (scenes of belly dancer, football game with locals). Shots of ships' galleys moves us to a minesweeper, where the third man, Harry is posted; as an Able Seaman he "does a bit of everything" including steering the ship and helping to haul in a dummy mine after an exercise. The minesweeper (M.1187 - HMS Upton, a RNR training vessel) sails on. Finally, Charley is introduced, a helicopter mechanic on HMS Albion, carrying helicopters and commandos. He makes a routine check on a Westland Wessex, which is then is lifted on deck where the rotors are "unfolded"; commandos appear on the deck lift and scramble to the helicopters, which take off. Charley's shore leave in Hong Kong: trip on Chinese junk, shopping, visit to Tiger Balm Gardens, meal in a floating restaurant and a Chinese opera. Film concludes with a shot of Tony's nuclear sub "blowing its way to the surface like a sperm whale", and a final reference to the choices available in the Royal Navy.