Meantime Astolfo has ridden off on the hippogriff to the earthly paradise, where he has interviews with sundry saints and apostles, and whence St. John conveys him up to the moon.  In that appropriate region the apostle explains that Orlando’s insanity is due to the fact he loves an infidel!  He further points out where the hero’s stray wits are stored, and directs Astolfo how to catch them in a vial and restore them to their rightful owner.  Then, before conveying Astolfo back to earth, St. John vouchsafes him a glimpse of the Fates, wearing the web of Destiny, which they cast into the stream of Oblivion, whence only a few shreds are rescued by poets!

On returning from this eventful trip to the moon, Astolfo joins the Saracens.  When they finally capture the mad Orlando, he produces his vial, and, making his friend inhale its contents, restores him to his senses.  His mad passion for Angelica being now a thing of the past, Orlando concentrates all his efforts to conquer the Saracens and triumphs in many a fight.

Meantime Rogero, on his way to join Bradamant, has been shipwrecked on an island, where a hermit converts him to the Christian faith.  While he is here, Orlando and Rinaldo arrive with their sorely wounded friend, Oliver, whom they entrust to the hermit’s care.  Not only is Orlando sane once more, but Rinaldo, having drunk the waters of the contrary fountain, no longer loves Angelica, and willingly promises the hand of his sister Bradamant to the new convert.  But, when brother and prospective bridegroom reach court, they learn Charlemagne has promised Bradamant to a Greek prince, to whom the lady has signified that ere he wins her he must fight a duel with her.  On hearing that the Greek prince is at present besieging Belgrade, Rogero hastens thither, and performs wonders before he falls into the enemy’s hands.  But the Greek prince has been so impressed by Rogero’s prowess that he promises him freedom if he will only personate him in the dreaded duel with Bradamant.  Rogero immediately consents to fight in the prince’s armor, and defeats Bradamant, whom Charlemagne thereupon awards to the Greek prince.

In despair at having forfeited his beloved, Rogero rides off to die of grief, but the Greek prince, riding after him to thank him, not only discovers the cause of Rogero’s sorrow, but generously relinquishes all claim to Bradamant and volunteers to witness her marriage to Rogero.  The courage shown by the bridegroom while at Belgrade has meantime so impressed the Bulgarians, that an embassy arrives to beg him to mount their throne.  But before Rogero can assume the Bulgarian crown he is forced to conquer and slay the boastful Rodomont, who envies his exalted position.