A chorus of local people on boats proclaims the upcoming wedding of Isoletta, daughter of Montolino, to Count Arturo of Ravenstal: (Men: "Voga, voga, il vento tace...e l'alma pace / Messaggiera dell'amor" / "Row, row, the wind has dropped...this blessed peace is the message of love".) But, together on the shore, Isoletta tells Baron Valdeburgo that she fears her Arturo has changed his attitude toward her and believes that he has fallen in love with a mysterious woman living as a hermit in a hut by the lake: (Duet: Isoletta to Valdeburgo: "Agli atti, al volto / non mortal, divina imago" / "From her gestures, her expression, she did not appear to be mortal, but rather a divine image". Valdeburgo, to himself: "Giovin rosa, il vergin seno / schiudi appena al ciel sereno" / "A newly bloomed rose has scarce opened / her virgin breast to the serene sky, / and already she wilts in pallor".) In the distance a crowd is heard following "La straniera" who has been seen from the lake shore. They curse her as a witch.