Uther-Pendragon becomes Overlord of Britain with the help of the enchanter Merlin and the knight Sir Ulfius. Uther-Pendragon marries the lady Igraine, a widow with two daughters: Margaise and Morgana le Fay. Morgana le Fay is a sorceress who marries King Lot of Orkney. Margaise marries King Urien of Gore.

Uther-Pendragon and Igraine have a son together—Arthur. While Arthur is an infant, Merlin tells Uther-Pendragon a prophecy: Arthur’s enemies will come after him when Uther dies. Merlin convinces Uther to hide Arthur with another family. Shortly after, as Merlin predicted, Uther-Pendragon dies of a fever. The realm falls into chaos with conflicts between kings, as well as highway robberies and murders.

After 18 years of chaos, the Archbishop of Canterbury asks Merlin to assist him in finding a new king. Merlin foresees a great king, of royal blood, who will bring peace. The Archbishop asks how they will find the king. Merlin suggests a magical trial, and the Archbishop agrees. Merlin creates the sword in the stone. In front of the cathedral, a huge marble block appears with an anvil on top, and a sword stuck deep into the anvil. The sword has a message engraved on it explaining that the person who removes the sword from the stone will become king.