The subject is taken from Boiardo's 'Orlando Inamorato', Book II, cantos viii-ix. The fair Margana, symbolising Fortune or Opportunity, holds captive Rinaldo and other paladins of Charlemagne. Orlando comes across her asleep by a fountain in a meadow. She awakes and dances round the fountain singing. Orlando is first captivated by the fairy's beauty but seeing her prisoners he pursues her in order to obtain the silver key to the dungeon in which they are confined. The chase leads him through forests, mountains and tempests but at last he catches the Fata Morgana by the forelock and wrests the key from her, though not without first having been delayed by Penitence, an old woman who scourges him for not having at once seized the fairy when he first discovered her asleep by the fountain.