When a group of Nationalists use an ancient artifact to bring a villain from Arthurian myth back from the dead to gain power, ex-monster hunter Bridgette McGuire escapes her retirement home and pulls her unsuspecting grandson Duncan, a museum curator, into a world of magic and mysticism to defeat a legendary threat.
ARTHUR VS. ARTHUR!Knowing that Grail Castle may be their best chance at survival, Bridgette, Duncan, and Rose hunker down and prepare for the worst.Elsewhere, the resurrected King Arthur challenges an arriving usurper to his rightful throne, another King Arthur, and raises an army of the undead to do it. But the new Arthur has the greatest knight of all on his side – Lancelot!