Junior doctor Simon Sparrow (Dirk Bogarde) gains a position at St Swithin's Hospital in London and ends up sharing 'digs' with a bunch of slightly older young medics, all of whom have failed the previous year on account of their inability to keep to the curriculum. Sparrow tries to find a balance between the antics of his new peers and the ever-terrifying Sir Lancelot Spratt, chief surgeon at St Swithin's and a man on the lookout for miscreant doctors wherever they may be. Menaced by the advances of his landlady's daughter, and feelings for one of the nurses, will Sparrow be able to qualify?

Re-enactment of the events surrounding the voyage in April 1949 of the Royal Navy frigate Amethyst along the Yangtse river, and the attempts of its crew to get vital supplies to a British Embassy isolated in civil war-riven China. Commander J.S. Kieran (Richard Todd) is forced to brave Communist artillery along the 140-mile stretch to freedom, losing many men en route.