A hall in the Doge’s Palace, Venice.
Venice, 1457. The Council of Ten and the Council of Three have assembled for a mysterious reason (introductory chorus «Silenzio, mistero »). Among their members is Loredano, an enemy of the Foscari, whom he holds responsible for the assassination of his parents. Jacopo Foscari, son of Doge Francesco, is brought before them from prison to stand trial for having illegally re-entered his home city from exile, to which he had been condemned after an unjust accusation of murder. While waiting to be introduced into the Council’s presence, Jacopo gazes out from the balcony at Venice, the memory of which was his only comfort during exile (scena and cavatina «Dal più remoto esiglio»). He then enters the Council hall, with no illusions of receiving clemency there.

Hall in the Foscari palace.
Lucrezia Contarini, Jacopo’s wife, is determined to go to the Doge and ask him to intervene in defence of his son. But her handmaidens restrain her (chorus «Resta... quell pianto accrescere»). For Lucrezia, in despair, it only remains to pray to heaven (cavatina «Tu al cui sguardo onnipossente»). When her friend Pisana tells her of the sentence handed down by the Council of Ten confirming Jacopo’s exile, Lucrezia vents her contempt and rails against the Venetian patrician class.

Hall as in scene one.
As they leave the judgement hall, members of the Council comment on the event: a letter, written secretly by Jacopo to the Sforzas, had made his banishment inevitable; the Doge’s son must return to exile in Crete (chorus «Tacque il reo!»).

The Doge’s private rooms.
Alone, the Doge bewails the fate of his son and deplores his own harsh condition as a father (scena and romanza «O vecchio cor, che batti »). Lucrezia enters, claiming that her husband is innocent and inveighing against the Ten. The Doge however has no other choice but to remind her of the law and of the letter by which Jacopo stands accused. Lucrezia can do no more than beg the Doge to pray with her (scena and duet «Tu pur lo sai, che giudice»).