Constance, in the year 1414. The crowd in the church intones a Te Deum in celebration of the overthrow of the Hussite heresy by an army led by Prince Leopold, nephew of the Emperor Sigismund. A section of the crowd is enraged by the fact that the Jewish goldmisth Eleazar is working on this public holiday. The provost would gladly have Eleazar and his daughter Rachel burnt at the stake, but Cardinal Brogni preaches clemency towards the same Jew who on an earlier occasion he himself had banished from Rome. This kind attitude, however, serves merely to increase the resentment and hatred in Eleazar’s heart. Leopold, who is secretly in love with Rachel but married to Princess Eudoxie, has been able to gain entry to Eleazar’s house, disguised as Samuel, a young Jewish painter. He serenades Rachel and persuades her to a rendezvous that evening. As fountains run with wine in the carnival and town people gather in groups, Eleazar and Rachel are seen in front of the church. The crowd wants to throw them into the lake, but they are saved by the disguised Leopold, much to the surprise of Rachel who fails to understand how her lover can influence the crowd to obey him. During the imperial procession Leopold returns to his family and joins the baptizing ceremony of his third child.
Passover (Seder) celebrations in Eleazar’s house. At the sharing of the matzah (consecrated bread), Rachel notices the movement with which Leopold gets rid of it. When the Emperor’s daughter, Princess Eudoxie, knocks at the door, the Jews quickly hide the holiday symbols. The princess wishes to obtain from Eleazar, as a gift for her husband Leopold, a magnificent chain that had belonged to the Emperor Constantine. As Eudoxie leaves, the Jews conclude the Seder. Rachel waits in anguish for Leopold, whom she has allowed to return. Rachel is troubled by the young man’s hesitation during the Seder and wonders whether he is deceiving her. Leopold confesses that he is a Christian and nevertheless begs her to elope with him. Eleazar, realizing that Leopold is a Christian, gives his blessing to his marriage to his daughter only because Rachel begs him. Yet now it is Leopold who realizes that he cannot marry Rachel and so he flees.
Rachel, who has followed Leopold to the palace, enters and finds Eudoxie and her children. She flings herself at the feet of Eudoxie, greatly moved by her beauty and her tears; the Jewess begs the Princess to employ her as a servant, suspecting that Leopold has left her for the Princess. At the imperial banquet Eudoxie presents Eleazar’s chain to Leopold, greeting him as her husband. But Rachel leaps forward, tears the chain from Eudoxie, and reveals the unforgivable crime for which Leopold and she are jointly condemned to death: he is a Christian, she is a Jew, and he is her lover. Eleazar anathematizes the iniquitous Christians for their constant readiness to exculpate their own but to show no mercy to others. All three are cursed and arrested.
Eudoxie visits Rachel in her prison cell and begs her to deny Leopold’s guilt and to save him. But Rachel decides to save Leopold by sacrificing herself alone. Her generosity and nobility of spirit make a deep impression on Cardinal Brogni, who has Eleazar brought before him in an attempt to save him from the sentence to be passed on him by the Council. If he recants, Rachel will be saved. Eleazar scorns him with hatred, and is set on vengeance. He reminds the Cardinal of the day when he lost his wife and little daughter in the pillage in Rome. That daughter has been saved by a Jew, and the secret will perish with Eleazar. Outside the crowd demands that the infidels be tortured.
The people of Constance and the Imperial family including Leopold gather to witness the execution of Eleazar and Rachel according to the Christian law. Rachel has exonerated Leopold, but despite the troubled Cardinal’s entreaties she will not renounce her faith even to save herself. She rejects the baptism that would save her. As Rachel is about to be executed Eleazar reveals to Brogni that she is his long lost daughter and follows her to his death.