In a time now lost in the mists of memory, the great King Arthur rules in the legendary citadel that is Camelot. His Knights of the Round Table perform acts of derring-do and spend their spare time jousting, much to the delight of the local citizens and especially to Princess Ilene, a guest at Camelot. Watching her from afar is a young, inexperienced squire called Valiant, and when the young Welsh princess is sent home to marry Prince Arn, Valiant contrives to accompany her masquerading as Sir Gawain. Meanwhile, the evil sorceress Morgan le Fey, sister to King Arthur, has convinced the tyrannical Sligon, ruler of the Viking kingdom of Thule, that he should steal Arthur's sword, the powerful and magical Excalibur, knowing that its loss could bring about Arthur's downfall. So into the fray comes Sligon's unstable and psychotic brother Thagnar, who manages to steal the sword. Pandemonium reigns. But Valiant is having problems of his own - kidnappers attempt to steal away the Princess, and after various skirmishes, including one with a mysterious character who lives in a cave and purloins treasure, women and other things of value, Valiant manages to return the Princess to her homeland - although he also manages to have a duel with the Princess' jealous fiancé, Prince Arn. All things converge as Valiant is finally informed of his heritage by the stranger from the cave... Boltar of Thule. He informs the lad that he is Prince Valiant, rightful heir to the kingdom of Thule, and with his help, Valiant returns to the land of his birth to rightfully claim what is his.