Under the Sun is set in the closing stages of World War Two in the South Pacific. Flight Lieutenant Edward Strickland is a young RAF Spitfire pilot flying sorties over the Carolines and their outlying atolls. On a dawn patrol he is shot down attacking a submarine and ends up on a remote island occupied by a small Japanese garrison, that has remained undetected throughout the war. The garrison's commander Captain Tadashi Hayama brutally interrogates his captive and a battle of wills develops between the two men. The scene is set for a contest where there will only be one victor. But events.