 Sesse and his crew come to Naples in pursuit of Martia; they disguise themselves as "Switzers" (Swiss mercenaries, common in Italy at the time) and take service under Ferrant and Ronvere.To obtain her vengeance on Virolet, Martia joins with Ronvere and is introduced to Ferrant; he fancies her, and seats her next to him on his throne.Sesse and his crew launch a rebellion, and the discontented populace rise with them; Ferrant and his supporters retreat to the tower of his castle.