In the waning days of Camelot, Merlin transforms his demon familiar Etrigan into a man, Jason Blood, who loses his memory of his Demon identity. By the 20th Century, Morgaine Le Fey, Merlin's adversary, has arisen anew and wishes to replenish her youth with Merlin's secrets. She forces Jason Blood to become the Demon again and to lead her to Merlin's tomb.