When Gwen was kidnapped by Morgana, she was taken to the Dark Tower and imprisoned in a room filled with Mandrake Roots, which tortured her with nightmarish hallucinations of her friends and loved ones laughing at her. Morgana visited regularly to give her food and sympathy, trying to convince her that she was only person she could trust. Gwen resisted at first, but her resolve slowly crumbled as the hallucinations intensified.
Meanwhile, after they discovered Gwen's disappearance, Merlin, Arthur, and the Knights of the Round Table embarked on a quest to rescue her. Percival and Leon suffered identical nightmares about the Tower during their journey, which led Merlin and Arthur to believe that Morgana had taken Gwen there to lure them into a trap. Sure enough, they arrived at the Tower to find that it was filled with booby traps, including one where flagstones on the floor reacted to pressure and released deadly arrows.
Using his sword to test the floor before stepping on it, Elyan safely crossed the room and decided to continue on alone. He found Gwen at the top of the Tower being guarded by an enchanted sword. Though she begged him to leave and save himself, Elyan engaged the sword in a duel and managed to defeat it. However, he was mortally wounded in the process and died soon afterwards in Gwen's arms (The Dark Tower).
- Series 3
- The Eye of the Phoenix (Mentioned only)
- The Dark Tower may be located in the Perilous Lands, as it was briefly shown on Arthur's map (The Eye of the Phoenix).
- According to Queen Mab, the tower only exists in one's mind. Because she often spoke in riddles, however, it is unknown exactly what she meant by this (The Dark Tower).
- It is possible that this location is based off of Barad-dur from J. R. R. Tolkien's The Lord of the Rings trilogy, as Barad-dur, in Elvish, also means "Dark Tower."