When Mordred reads Merlin's diary he discovers that Arthur, Gwaine or Lancelot could be his father. Mordred invites them to his wedding without telling Merlin to find out who is his father, which delights them because all three never stopped loving Merlin. While Mordred is trying to work out which man is his father, Arthur, Gwaine, and Lancelot all try to win Merlin back. What no-one knows is that another ex from Merlin's past who abused Merlin has come to the island and is determined to do anything to make Merlin theirs again.