Season synopsis
Contains spoilers for this season and earlier seasons.
Three years into Arthur’s reign, Merlin sees a vision of his king’s death while Morgana holds Camelot’s knights captive at Ismere. Mordred returns and saves Arthur, earning a knighthood despite Merlin’s fears about his future. When Mordred is later wounded, the Disir offer Arthur a choice: embrace magic or face their judgment. Hoping Mordred will die, Merlin urges Arthur to reject magic; instead, Mordred recovers, leaving Merlin’s attempt to prevent the prophecy working against him.
Morgana abducts Gwen and breaks her resistance through confinement and mandrake-induced visions. Elyan dies rescuing his sister, but Gwen returns secretly serving Morgana and attempting to kill Arthur. Merlin uncovers the enchantment and, disguised as the sorceress Dolma, helps Arthur bring Gwen to a sacred lake. Her willingness to enter its waters frees her from Morgana’s control, and she returns to Camelot as herself.
Mordred’s loyalty finally breaks when Arthur executes Kara, the woman he loves, after she refuses an opportunity to repent. He joins Morgana and identifies Merlin as Emrys. Morgana strips Merlin of his magic before the battle at Camlann, but Balinor’s spirit helps him recover it in the Crystal Cave. Merlin reaches the battlefield and routs Morgana’s forces; Mordred nevertheless mortally wounds Arthur, who kills him in return.
Merlin reveals his magic to Arthur and takes him toward Avalon, hoping to heal the wound. Gwaine dies after Morgana tortures him for their whereabouts. When she intercepts Merlin and Arthur, Merlin kills her with Excalibur, but Arthur dies before they reach the lake. Kilgharrah promises that Arthur will return when needed. Merlin sends his body across the water and returns the sword to the lake. Gwen rules Camelot, while a final glimpse of modern-day Merlin shows him still waiting.