With King Uther's sudden death, chaos threatens to engulf Britain. The sorcerer Merlin has visions of a dark future and installs young and impetuous Arthur, Uther's unknown son and heir raised as a commoner, as the new king. The two install themselves in Castle Camelot with their allies, which include Arthur's biological mother, his foster brother, and a quartet of loyal warriors. From Camelot, Arthur tries to build a new and better Britain, where people can live in peace. Meanwhile, Arthur's cold half-sister Morgan plots to take the crown from him. Banished by Uther, who was responsible for her mother's murder to put Arthur's mother on the throne, Morgan is responsible for Uther's death and wants to rule as his successor. Aided by her loyal maid Vivian and the devious nun Sybil, Morgan takes up residence in Castle Pendragon, from where she schemes against Arthur.
Uther's daughter Morgana returns from banishment and poisons her father. Merlin arrives too late to save the king but gets Uther to acknowledge his illegitimate son on his deathbe…
Morgana faces opposition in her alliance with King Lot. Meanwhile, Arthur acquires the sword in the stone and is crowned King.
Morgan invites Arthur to a feast and Merlin accompanies him. While the temptress delays Merlin, Arthur returns to Camelot, drawn by his fascination with Guinevere. Meanwhile, Kay …
Whilst Guinevere wants to leave Camelot with Leontes, he's obliged to stay as one of Arthur's knights being trained by brilliant strategist Gawain, who breaks Arthur's sword in co…
Arthur and his knights arrive at a village where the head man has been killed and his alleged murderer Colfur is about to be lynched. Arthur insists his trial take place at Camelo…
Morgan impresses the supplicants who come to her court but is visited by a woman who claims Sibyl set fire to a convent in which her daughter died, requiring Morgan to punish the …
Despite the misgivings of Igraine and Kay, Arthur and his inner circle attend a banquet given by Morgan as a sign of reconciliation, during which her castle is attacked. Arthur's …
Morgan fools Camelot with her disguise, even Merlin. However, after Redwald, a little orphan boy, whom she and Merlin have helped celebrate his birthday, accidentally dies because…
Morgan makes her escape, leaving a puzzled Igraine believing she is going mad until Merlin explains Morgan's deception. They go to Castle Pendragon to confront her but end up as h…
Morgan enters Camelot with her prisoners, claiming that they're traitors and that only she can save the realm from the marauding bands. Arthur does a sterling job of holding the a…