In their eagerness to collect once and for all the thirteen objects scattered throughout Britain, Merlin and Nimue commission Derfel Cardan to obtain the last of them: the mythical sword of King Arthur, Excalibur. As Arthur's men prepare to face the decisive battle against the Saxons by invoking their gods, Merlin and Nimue initiate a bloody ritual involving the sacrifice of a king. However, through strange paths in which the captivity of Geneva at the hands of Morgana crosses, the sorcerers and King Arthur will join forces to face a new invasion of Dumnonia launched by the Saxons, whose outcome will be the terrible and most violent battle of Camlann.