"Merlin: The Return" is the story of the battle between good and evil. The dark forces of Mordred are pitted against the mythical sorcery of Merlin. Mordred and his mother Morgana have been imprisoned in another world for the past 1500 years while Merlin's magical powers kept them at bay. However, in the present, a scientist accidentally finds the gateway to the other world and is about to release Mordred into 20th Century life. Arthur is reawakened from his slumber and together with Merlin, tries to find a way to stop Mordred from re-entering this world.