King Arthur has gone mad, fueled by his jealousy toward Lancelot for romancing his wife, Queen Guinevere. In his desperation, Arthur has been tricked by his sister, the all-powerful sorceress Morgana Le Fey, to open the Hellgate and allow all forms of demons to enter the world. Meanwhile, Morgana has captured Guinevere and holds her hostage on the magical island of Avalon.