As the marchesa held consultations with Schedoni, Ellena was suffering from exhaustion that came as a consequence of the long and severe anxiety she had endured. Two weeks pass before her spirits revive. While visiting her daily at the grate of the convent, Vivaldi avoids renewing the subject of their nuptials until she has sufficiently recovered.

In turn, his open, undisguised distress awakens her affection and gratitude, leading her to question her reluctance. She begins to wonder if she is not in fact unjust and selfish, unwilling to make any sacrifices for his tranquility. Likewise, she has questioned if her virtues, when carried to an extreme, are not in fact vices, and her sense of dignity little more than narrow pride.

As Vivaldi senses a growing receptiveness on her part, he renews his pleas for an exchange of vows, to which she begs him not to return until the following morning. In the meantime, he makes arrangements for their wedding and their return to Naples. After she consents to their nuptials the next morning, they head to a chapel belonging to a Benedictine convent. On their way to the church, the gloominess of the evening and the thunderclouds alarms her, while the sight of cypresses by the chapel makes her feel ill at ease with their funereal associations.

Upon arriving at the dusky chapel, Ellena looks around fearfully, expecting to find a lurking observer even as she finds it unlikely. For a brief moment, however, she catches the disturbing sight of a human face at a casement window. Noticing a dark countenance by a door which is quickly shut, she lays a fearful hand on Vivaldi, telling him that they are being observed. He brushes her fear aside before pressing the officiating priest to conclude his orison and to shut the doors. The priest replies that the doors to a sanctuary can never be shut.

As the priest begins the wedding ceremony, the door is opened by several armed men. Vivaldi draws his sword to protect Ellena as they approach. Suddenly, a loud voice orders Vivaldi and Ellena to surrender in the name of the Inquisition. When Vivaldi and the priest demand proof from the men, the latter present a black scroll, with the chief officer explaining that Vivaldi has stolen a nun from a convent. Vivaldi begins to suspect that Schedoni is behind the summons.

As the officers tear Ellena away, the other men take Vivaldi and Paulo to the Benedictine convent for the treatment of their wounds.