Venetian morality guardians burst into the apartments of notorious libertine Giovanni Jacopo Casanova. He is indicted for atheism, possession of indecent literature, and fornication – the last a hard charge to shake off, as he happens to be in bed with an equally indecent woman. As his friend Senator Bragadin tries to intercede on his behalf, the imprisoned Casanova is tormented both by wicked jailer Lorenzo and by memories of his lost love, the innocent country girl Cristina, whom he betrayed.