Venice, 1755. Giacomo Casanova, just returned from exile in Vienna, threatens to kill hearts and create havoc in the city with his unparalleled charisma. Meanwhile, the Doge Francesco Loredan is in poor health and the Inquisitor Pietro Garzoni plots to influence in his favor the succession to the Dogado. In this regard, the latter intends to get rid of Casanova, because it could ruin his plans, and to the purpose he entrusts the evil Zago. While at Cantina do Mori, the Prince of Seductors meets an old flame: the beautiful Gretchen, who leads him to the palace of Countess Margarethe von Steinberg, for whom she works as a waitress. Here, Casanova meets the great lady and is challenged by her in a singular bet: if he succeeds in seducing the young Francesca Erizzo, daughter of one of the elders of the city, she - Margarethe - will be his for one night.

Moriondo, a bachelor in his mid-forties, has spent half his life on billiard tables around the world and returns to his home town after fifteen years. Tired, penniless, with a failing budget, he returns above all to rediscover part of what he suffers from having lost: the feelings, the enthusiasm, the memories of youth. Instead he finds many people willing to remain silent and some friends who escape him, like Mambretti. He finds, above all, a mysterious hint of death. In fact, he learns that five years earlier a friend of his, Count Luigi Ambrosi, was killed with a singular system. A cyanide egg. The investigations and the trial recognized a certain "Panozzo", administrator of Count Ambrosi, as the perpetrator of the crime, but the wife of the killed man continues to maintain that an innocent man was convicted.