In medieval Italy, a greenhorn knight, Guerrando da Montone, receives a grant of all the land he can cover by horse in one day. Included in this territory is the house of Boccadoro, a peasant girl long infatuated with Guerrando, who now asks to be claimed as his property. Guerrando wants to share her with his servant, however, and she refuses his advances until marriage. Guerrando agrees to the marriage with the intention of burning Boccadoro as a witch when he grows tired of her, but she takes revenge and waits 3 days before she will allow the marriage to be consummated. At the moment of union, Guerrando is called away to the Crusades, and he locks Boccadoro in a chastity belt. Infuriated, she disguises herself as a knight and sets out to find him. In battle, she defeats another knight, Drogone, who then pledges to aid her in finding Guerrando. They finally catch up with Guerrando, but the key to unlock the belt is misplaced. Boccadoro and Guerrando are taken prisoner by Saracens. The Sultan of Bari wants to keep Boccadoro for his harem, but she escapes with Guerrando. They finally find the key but discover that it doesn't fit the lock. Drogone returns the right key, however, and reveals that he is actually King Ludwig of the Holy Roman Empire. He then leaves Boccadoro and Guerrando to fulfill their marriage vows.