On a frosty morning centuries ago in the magical kingdom of Camelot, King Arthur prepares to greet his promised bride, Guenevere. Merlyn the magician, the king's lifelong mentor, finds Arthur, a reluctant king and even a more reluctant suitor, hiding in a tree. Arthur reveals exactly how nervous he is as he sings “I Wonder What the King Is Doing Tonight.”
Guenevere, equally nervous, has avoided the welcoming committee and is hiding in the forest. At the conclusion of her song “The Simple Joys of Maidenhood,” Arthur falls out of the tree. Guenevere is unaware that she is sparring with the king, and Arthur, captivated by her, sings of the many magical qualities of “Camelot.” Soon, his identity becomes evident, and, already having charmed one another, they go off hand-in-hand to be wed. Along with his new Queen Guenevere, Arthur settles into an idyllic life of peaceful ways, might for right, and the eventual formation of his famous Round Table.
As news of Arthur's new order spreads across the continent, Lancelot finds his way to Camelot singing “C'est Moi” and proclaiming himself to be the most obviously suited of all knights to sit at Arthur's table. As Lancelot arrives, Arthur's court, led by the beautiful Guenevere, is enjoying “The Lusty Month of May.” Guenevere finds him insufferable and even mocks him and arranges to have three of Arthur's best knights oppose him in a jousting contest.
But before the jousting contests can begin, the comic Pellinore arrives, rusted up in his armor and looking for a cause. The old knight soon sees that the Round Table is the perfect place for him and quickly becomes a favorite of the king.
The contests now begin, and Lancelot proves the victor. In the process, however, Sir Lionel is killed. Lancelot, through is strange powers of purity and faith, revives Lionel as the court looks on. Guenevere is profoundly moved. At the same time, Lancelot finds himself secretly falling in love with Guenevere. Her new and mixed feelings are expressed as she sings “Before I Gaze at You Again.” Arthur insists that Lancelot be knighted immediately.
Two years pass.. Lancelot and Guenevere must now deal with feelings they can no longer deny, as Lancelot sings “If Ever I Would Leave You.” The once innocent and happy mood darkens even more as Arthur becomes aware of the growing and obvious feelings between his beloved queen and his trusted knight.
Next, to add to the mood, Mordred, Arthur's illegitimate son, arrives with the intention of discrediting his father and winning the throne for himself. His opinion of Arthur's dreams of honor and peace are revealed as he sings “The Seven Deadly Virtues.”
Guenevere, still faithful to Arthur, tries to lighten the burdens of her disillusioned husband as they sing “What Do the Simple Folk Do?”
Arthur's knights, having grown weary of talk and inaction, cry “Fie on Goodness!” Mordred confronts Arthur in the forest and Arthur agrees to spend the night away from Camelot to prove his trust of Lancelot and Guenevere. However, Lancelot's ill-timed visit to Guenevere's bedchambers that evening suits Mordred's trap perfectly. Guenevere is quickly arrested for treason, while Lancelot escapes.
Guenevere is sentenced to burn at the stake under Arthur's own code of justice, and he is helpless to intercede-although he cannot bring himself to give the order to light the flames. Lancelot rescues her at the last moment and takes her to France. Alas, Arthur is now forced to make war upon the friend he so dearly loves.
Just moments before going into battle, Arthur finds a stowaway boy whose only desire is to grow to manhood and become a knight of the Round Table. Arthur sees in the boy that his dream of peace and right has not died. He knights the boy and sends him running behind the lines with a charge to tell the story far and wide in order that generations to come might remember that once there was a wondrous place called Camelot.