Camelot

Morgana, Uther's daughter, returns after being exiled and poisons him. Merlin arrives just in time for Uther to recognize his illegitimate son before dying. Merlin then takes the young Arthur to the ruins of Camelot.

Morgana struggles to maintain her alliance with King Lot, facing growing resistance. At the same time, Arthur successfully pulls the sword from the stone and is declared king.

Morgan invites Arthur to a feast, with Merlin accompanying him, but Merlin is detained by a mysterious woman while Arthur becomes captivated by Guinevere and returns to Camelot. At the same time, Kay and Leontes search for a renowned warrior to join Arthur's growing forces.

Guinevere wishes to leave Camelot with Leontes, but he must remain to train as one of Arthur's knights under the strict guidance of strategist Gawain, who demonstrates his skill by breaking Arthur's sword. Merlin, having advised Arthur to control his feelings for Guinevere, seeks to commission a new sword from the reclusive bladesmith Caliburn, a widower living with his daughter.

Arthur intervenes when a man named Colfur is about to be lynched for the murder of a village leader, insisting he be tried in Camelot to uphold the principles of justice. With Guinevere speaking to Colfur's young daughter, new complexities in the case come to light, challenging initial assumptions.

Morgan gains respect from those who appear before her but faces a challenge when a woman accuses Sibyl of burning a convent where her daughter perished, prompting Morgan to take action against the nun. Meanwhile, Arthur travels with Guinevere to see her ailing father, during which he resists personal temptations.

Arthur and his advisors attend a banquet hosted by Morgan in an effort to mend relations, despite objections from Igraine and Kay. The event is disrupted when Morgan's castle is attacked, though Merlin suspects the assault is a ruse staged to create chaos.

Morgan disguises herself as the queen and successfully deceives Camelot, including Merlin, but her ruse begins to unravel after a young boy named Redwald, whom she and Merlin had helped, dies under mysterious circumstances, causing Merlin to suspect her. Meanwhile, Vivian releases Igraine to confront Morgan, who has revealed sensitive information about Leontes's wife to the king.

Morgan escapes, leaving Igraine confused and doubting her sanity until Merlin reveals the truth. Igraine and Merlin pursue her to Castle Pendragon, where they are captured. Meanwhile, Leontes, having discovered his wife's infidelity, decides to leave Camelot but later joins Arthur and the knights to defend Bardon Pass.

Morgan arrives in Camelot with captured prisoners, accusing them of treason and warning of marauding threats. Arthur successfully defends the city using clever traps until reinforcements arrive to defeat the invaders.