Most of the book "takes place on the isle of Gramarye", and it chronicles the raising and educating of King Arthur, his rule as a king, and the romance between Sir Lancelot and Queen Guinevere. It ends immediately before Arthur's final battle against his illegitimate son Mordred. Though White admits his book's source material is loosely derived from Sir Thomas Malory's Le Morte d'Arthur (The Death of Arthur), he reinterprets the epic events, filling them with renewed meaning for a world recovering from World War II.
The book is divided into four parts:
- The Sword in the Stone (1938)
- The Queen of Air and Darkness (1939) (published separately in somewhat different form as The Witch in the Wood)
- The Ill-Made Knight (1940) (which mainly deals with the character Lancelot)
- The Candle in the Wind (first published in the composite edition, 1958)
A final part called The Book of Merlyn (written 1941, published 1977) was published separately (ISBN 0-292-70769-X) following White's death. It chronicles Arthur's final lessons from Merlin before his death, although some parts of it were incorporated into the final editions of the previous books.
An oft-quoted passage from the book is the story that the badger calls his "dissertation", a retelling of the Creation story from Genesis.