During the Dark Ages, England is divided. A legend arises about Merlin, the sorcerer, and a king, who will wield Excalibur, “the sword of power,” to unite the kingdom. When Uther Pendragon wins multiple victories, Merlin orders him to negotiate a truce with the Duke of Cornwall. Prior to the meeting, Merlin conjures the Lady of the Lake, who rises from the watery depths with Excalibur. Brandishing Excalibur, Uther demands Cornwall yield to him as king and, in return, promises Cornwall the land from his castle to the shore. Cornwall accepts and holds a banquet, but when Cornwall’s wife, Igrayne, dances, Uther’s lust for her ends the truce. As Cornwall rides into battle, Uther demands that Merlin cast a spell allowing him to make love to Igrayne, and agrees to give Merlin the child conceived during the encounter. Merlin’s spell changes Uther’s countenance to Cornwall’s, and the ruse fools Igrayne, although her young daughter, Morgana, sees the truth. Igrayne learns Cornwall was killed during the night, and when she gives birth to Arthur Pendragon, Merlin takes the child. Uther chases Merlin, but is ambushed by Cornwall’s men. As Uther dies, he rams Excalibur into a stone, and Merlin declares that the man who draws the sword from the stone shall be the true king. Years later, knights joust for the opportunity to pull the sword from the stone, and the teenaged Arthur is squire to his older brother, Kay. Leondegrance wins the first joust, but cannot free the sword. When Kay’s sword is stolen, Arthur chases the thief, and, needing a sword, pulls Excalibur from the stone. His father orders him to put it back, but no one else can free it. When Arthur retrieves the sword again, Leondegrance declares allegiance, but other knights suspect trickery. Merlin arrives and, as Arthur follows the sorcerer into the woods, he learns of his true parentage and his destiny. The next day, Arthur and Merlin travel to Leondegrance’s castle where Arthur’s supporters are under siege. Leondegrance’s daughter, Guenevere, observes Arthur fight his way onto the castle’s walls, then leap from the castle onto Uryens, demanding the knight’s allegiance. Everyone watches as Uryens declares that he will not yield to a squire, and, to their surprise, Arthur hands Excalibur to Uryens and asks to be knighted. Impressed by Arthur’s courage, Uryen’s knights him and kneels to his king. Later, at a celebratory banquet, Arthur is attracted to Guenevere and listens to Merlin’s prediction that the two will marry, while ignoring the caution that she will betray him with a trusted friend. Arthur’s knights win many battles in their fight to unite the kingdom. Later, they are stopped by Lancelot, a knight seeking a king worth serving, who refuses to let them pass. Arthur’s knights fail against Lancelot, so Arthur challenges him. Arthur is knocked down, but refuses to yield and demands a fight to the death. Arthur calls upon Excalibur’s power and knocks Lancelot down, breaking Excalibur on the knight’s lance. Realizing his pride destroyed Excalibur, a despondent Arthur throws the sword into the water, but the Lady of the Lake rises, and offers the restored sword to Arthur. Lancelot swears allegiance to Arthur, and they are victorious in uniting the land under one king. When Merlin gathers the knights in a circle to commemorate the occasion, Arthur declares they will always join in fellowship at a round table, and announces his upcoming marriage to Guenevere. As Lancelot escorts Guenevere to the wedding, their mutual attraction is evident. He admits he loves her as his queen and the wife of his best friend, and will never love anyone else. At the wedding, Arthur’s half-sister, Morgana, asks Merlin to teach her the secrets of a necromancer; she is excited by the power, but Merlin claims the days of their kind are ending. Later, Lancelot meets Perceval, a young man who desires to be a knight. Lancelot leads Perceval to Camelot, Arthur’s grand castle, and places him in training to be a squire. When Lancelot sees Guenevere walking with Morgana, he leaves again, and Morgana notes Guenevere’s disappointment. At dinner, Morgana whispers to Gawain that Guenevere and Lancelot are in love. Gawain is furious at Lancelot’s continual absence from the round table, and announces that Lancelot is driven away by Guenevere’s desires. The queen immediately protests her innocence, and although Arthur is furious, he cannot champion Guenevere because he is king and, therefore, the judge. Since Lancelot also stands accused, Arthur insists that he must champion Guenevere in two days. That evening, Guenevere argues that Arthur should defend his wife, but he insists his role as king is the first priority. Elsewhere, Lancelot prays to be purged of his love for Guenevere so that he can defend her. During the night, he battles with himself and is stabbed. At the appointed time, Lancelot is missing and Gawain demands justice. When no knight will champion Guenevere, Perceval steps forward and Arthur knights him. Perceval prepares to joust with Gawain, but Lancelot arrives. Although blood flows from Lancelot’s wound, he prevails over Gawain, and then collapses. Arthur orders Merlin to use his magic to save the knight, and Lancelot joins them for dinner at the round table. When he leaves to rest in the forest, Guenevere joins him. Arthur asks Merlin’s advice about Lancelot and Guenevere, but the sorcerer offers no counsel, claiming that his days in this world are over. Morgana follows Merlin into a deep cave, insisting that he promised to teach her the powerful “charm of making.” Merlin hopes to trap Morgana with a spell, but in the cave they see the image of Arthur approach Lancelot and Guenevere in the forest, and, as Arthur thrusts Excalibur between the sleeping couple, it simultaneously wounds Merlin in the cave. Weakened, Merlin reveals the charm of making to Morgana and she traps him with magic. In the woods, Guenevere and Lancelot awaken and are horrified to discover Excalibur between them. In the castle, Morgana uses her newfound power to transform herself into the image of Guenevere, makes love to Arthur, and conceives a son, Mordred. Later, when Arthur prays to be saved from Morgana, he is struck by lightning and seriously wounded. As famine sweeps the land, a weakened Arthur orders his knights to find the Holy Grail for redemption. Years pass, and several knights perish on the quest, including Gawain. Perceval meets Mordred, now a young boy, who leads the knight to Morgana’s lair. Perceval is hung within a forest of dead knights and, as he slips into unconsciousness, the spurs of the knight hanging above him rub against Perceval’s rope. In his delirium, Perceval has a vision of the grail floating toward him at Camelot as a voice asks for the secret of the grail, but the knight is jarred back to consciousness when the rope breaks, and he believes he failed the quest. For years, Morgana grooms Mordred to become king, and casts a spell that no weapon forged by man can harm him. Mordred arrives at Camelot, but Arthur cannot give him the land, only a father’s love. Mordred announces the quest knights have failed and that he intends to take Camelot by force. As Mordred and his men leave, they attack Uryens. When Perceval reaches the dying knight, Uryens orders him to continue the quest. Perceval finds a disheveled, crazy Lancelot, but is pushed into a stream and swept away before he can speak with his friend. As Perceval sinks beneath the water, he has another vision of the grail. Perceval acknowledges that the grail serves Arthur, who is one with the land, and obtains the chalice. When Arthur drinks from the grail, his strength returns and the land rejuvenates. As the knights prepare to fight Mordred’s army, Arthur visits Guenevere at a nunnery, asks for her forgiveness and learns she has kept Excalibur safe for him. Arthur prays for Merlin’s help, freeing the sorcerer to reach Arthur in dreams. Merlin also appears to Morgana in her sleep, questions if she spent her stolen magic to keep herself looking young, and tricks her into casting a heavy mist into Mordred’s camp, putting them at a disadvantage. Mordred rushes into Morgana’s tent, discovers she has transformed into an old crone, and murders his mother. During the battle, Lancelot joins Arthur’s knights as they prevail over Mordred’s army. Lancelot receives Arthur’s forgiveness and dies as a knight of the round table. As the fog lifts, Mordred stabs Arthur, who slides himself closer on Mordred’s sword, and kills his son with Excalibur. A dying Arthur orders Perceval to throw Excalibur into calm water, and Perceval reluctantly obeys. The Lady of the Lake catches the sword and descends beneath the surface to await the time when another true king appears and Excalibur rises again.