George is the foster son of Sybil, an elderly sorceress. She raised him after his royal parents died of the plague when he was an infant. He has fallen in love with Princess Helene, though they have never met.
Helene is kidnapped by the wizard Lodac, who brazenly informs her father that he intends to feed her to his pet dragon in seven days. George wants to go on a quest to liberate his lady love, but Sybil believes he is too young. She tries to distract the youth by showing him a magic sword, a steed, an invulnerable suit of armor, and six magically frozen knights whom he will command when he turns 21. The impatient George, however, tricks Sybil and locks her in a cellar, then leaves with the magical implements and revived company of knights.
Sir George and his party appear before the King and insist on journeying to Lodac's castle to rescue Helene, against the opposition of Sir Branton, a knight who had previously volunteered for the perilous quest. The King promises the rescuer his daughter's hand in marriage and half his kingdom.
Seven curses bar the path to Lodac's castle. First, they encounter an ogre, who slays Sir Ulrich of Germany and Sir Pedro of Spain. When George tries to save Sir Anthony of Italy from a swamp, Branton treacherously kicks him into the swamp as well. Anthony is killed, but George survives with the help of his magic sword.
Later, Branton meets secretly with Lodac. Branton is in possession of a magic ring that had belonged to Lodac which the magician wants back desperately. The kidnapping was planned by the two men in order to secure Helene as Branton's bride, in exchange for the return of the ring to Lodac. When Sir Dennis of France discovers Branton and Lodac together, Lodac prepares a trap. Mignonette, a beautiful Frenchwoman, distracts Sir Dennis, then suddenly turns into an ugly hag who attacks him. George arrives and saves Sir Dennis with his magic shield.
Lodac finally becomes aware that George is being aided by magic. He contacts Sybil and mocks her abilities. Insulted, she tries to cast a spell to help George, but inadvertently strips away all of his magical protections.
Sir Dennis and Sir James of Scotland perish when they reconnoiter ahead. Branton then leads George and Sir Patrick of Ireland into a trap, revealing his partnership with Lodac before sealing them in a cave with deadly green apparitions. Patrick enables George to escape at the cost of his own life.
George sneaks into Lodac's castle and rescues Helene, but they are soon captured. The magician gives Helene (actually the hag in disguise) to Branton. Once Lodac has his ring back, he uses magic to put Branton's head on a plaque on the wall. George is tied up, but escapes with the help of some shrunken prisoners. Sybil arrives and finally remembers the spell that restores George's powers, enabling him to slay the two-headed dragon and save Helene. Sybil steals the ring while Lodac is distracted. When the magician threatens the young couple with the seventh curse - himself - Sybil transforms herself into a large panther and kills him. The movie ends at Helene and George's wedding. When the six knights are returned alive, George's happiness is complete.
- Basil Rathbone as Lodac
- Estelle Winwood as Sybil
- Gary Lockwood as George
- Anne Helm as Princess Helene
- Liam Sullivan as Sir Branton
- Jack Kosslyn as The Ogre
- Merritt Stone as The King
- According to the Trivia section of imdb.com, the Variety review dated April 11, 1962 provides a cast list which includes "Pinhead No.1" played by "Dick Kiel", indicating that actor Richard Kiel makes an un-credited appearance.
- In addition to her credited role in the mask as "The Hag", Vampira - as Maila Nurmi - also appeared un-credited in the role of the sorceress who kidnaps Princess Helene.
- Stuntman/actor Leroy Johnson (Sir Ulrich of Germany) had his dialog dubbed by voice specialist Paul Frees.
- Best Brains acknowledged (in the Mystery Science Theater 3000 Amazing Colossal Episode Guide) that "this is actually a pretty good movie."
- The Magic Sword of this movie is the sword Ascalon which was indeed the weapon St. George used to slay a dragon in the legend upon which this movie was based (though in some versions it was a lance).
- Like many movies based off myths and legends, many story elements were changed as well as adding new characters (like Lodac, Sybil and the mystical knights accompanying George) not from the original legend.
- This film became a RiffTrax presentation in 2015.