Percival is suddenly drawn into the world of spirits that reside in Behemoth and learns the origins of his existence. Unable to accept this truth, Percival returns to his original world, where Mortlach and others stand in his way. As the door to Camelot finally appears, the Four Horsemen of the Apocalypse, each with their own unyielding missions, clash with the knights of Camelot. (thetvdb.com)