Legend holds that when Britain is in its darkest hour, King Arthur will return to save the country, if not the world. That legend is dead wrong. When a Grove of Druids sacrifices the lives of a group of innocents, including the fiancée of a member of SEAL Team 666, the ancient king is brought back from the dead and sets his sights on subjugating humanity and cleansing his land of all who are not true Britons. Because of political sensitivities, Triple 6 is ordered to stand down, but that order is ignored when one of the team seeks his own vengeance. Now, the members of America's elite supernatural-hunting force must decide what is more important: their orders or their loyalty.