This drama is adapted from the story of King Arthur and the magician Merlin, and is jointly produced by BBC Wales and Shine Films. One year after Merlin (Colin Morgan) became the Dragon Slayer, Uther sent Arthur to lead the army to search for Morgana's whereabouts and brought Morgana back to the Kingdom of Camelot. At this time, Morgana is no longer the Morgana of the past. She is now a spy planted in the Kingdom of Camelot, attempting to weaken the core power of the Kingdom of Camelot and kill Uther. Morgana's evil plan was repeatedly stopped by Merlin, and she became Merlin's opponent invisibly. Once again, by chance, it was learned that she was actually Uther's biological daughter, and had the right to overthrow Uther and Arthur to inherit the throne of the Kingdom of Camelot. With the help of her sister Morgause, Morgana used various means to try to frame Arthur and others, and Arthur's future and the future of the kingdom will fall into dire straits...