High King Uther banishes his son, Arthur, who rescues a dying boy named Derfel; Arthur entrusts Derfel to Merlin and Nimue; Uther has a new heir, but Merlin receives a dark vision for the future.

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

Arthur takes Gundleus prisoner and learns that Gundleus' uncle Gorfydd is preparing for war; Nimue begins to plan her revenge.

Nimue comes back to Avalon and Merlin finds her; Owain and Derfel go to King Cadwys to collect taxes, but he persuades Owain to instead raid a nearby mine to pay off the money.

Nimue aborts her pregnancy and is later found by Merlin, who subsequently helps her; Derfel is uneasy about the attack on the mine that Owain is concealing; when Tristan shows up, he demands retaliation, but Owain claims he is innocent.

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