The magical sword of Excalibur starts off in the hands of British lord Uther Pendragon (Gabriel Byrne) and then, years later, finds its way to his bastard son, Arthur (Nigel Terry), the knave destined to become king. Aided by the sorcerer Merlin (Nicol Williamson), Arthur fulfills his fate by bringing together the Knights of the Round Table at Camelot and unifying the country. However, this flawed monarch faces greater tests ahead in pursuit of love, the Holy Grail and his nation's survival.