Kung Uther rasar mot sin oäkta son Arthur och förvisar honom. Arthur hittar sedan en ung pojke, Derfel, som är nära döden. Han lämnar Derfel till trollkarlen Merlin och hans lärling, druidinnan Nimue.

An untimely death leads Merlin to locate Arthur and urge him to come back to Britain; chaos ensues when Gundleus assaults Avalon.

Arthur takes Gundleus prisoner. Nimue struggles with the trauma of her rape and plans to kill Gundleus. Arthur learns that Gundleus' uncle Gorfydd is preparing for war. Nimue tries to pull Derfel into her plans, but Derfel can't betray Arthur.

Nimue returns to Avalon, where she is found by Merlin. Derfel and Owain travel to collect taxes from King Cadwys. Gundleus returns to Caer Cadarn.

Derfel feels uncomfortable about the attack on the mine – which Owain is keeping a secret. Nimue is discovered by Merlin who helps heal her. Tristan arrives demanding retribution but Owain denies his guilt.

Arthur and the tribe kings enter peace talks. Arthur meets Guinevere, Ceinwyn's lady-in-waiting, while traveling.