The action takes place in Cologne or nearby in the early 16th century.
Returned to Europe from America, Ruprecht, a knight, stays at a shabby inn in Germany. He hears some woman squealing in the next room, she is tortured by visions. When Ruprecht comes to help her, she – her name is Renata – suddenly calls the knight by name and tells him her story. Since her childhood, a fiery angel, Madiel, has appeared to her, and she has been in love with him. When grown up, she finally asked for his physical love. Madiel, in response, glowed in fury, but agreed to return in human form and later Renata met Count Heinrich. The count took her off to his castle where they were happy. One morning Heinrich left unexpectedly and failed to return. The forsaken young woman has been in search for her love for many days, and demons chase her. The innkeeper tells Ruprecht that her strange lodger passes for a witch and brings along a soothsayer who foretells Renata’s horrible future.
Ruprecht follows Renata in search for the count. He soon falls in love with her and swears to serve her faithfully. However, she steeps herself in demonological discourses and can only think how she could return her beloved, whether Heinrich or Madiel. In the room where they stay, the mystic knocks are heard at the door; thus the demons say that Heinrich is on the threshold, but no one comes in. Jacob Glock, a bookseller, arranges a meeting with the famous philosopher and powerful sorcerer Agrippa von Nettesheim whom Ruprecht queries about secrets of magic.
In front of Count Heinrich’s house Renata pleads with him vainly to let her in. She sees Ruprecht returning from Agrippa’s lair and, greatly affronted, begs to be avenged and demands that the knight challenge and kill Count Heinrich. When she sees Heinrich on his balcony, she believes again that he is the fiery angel and tells Ruprecht not to attack him. So, the duel is one-sided, as Heinrich easily overcomes Ruprecht and injures him heavily. Raving in fever, Ruprecht seems to hear the laugh of the red men with whom he fought in America.
When Ruprecht recovers, Renata says that their relationship must be broken off and insists on her joining a convent to better herself and for her soul’s sake. Ruprecht goes to a tavern to drown his grief in wine and meets Faust and a friend of his, Mephistopheles. They are travelling over Europe and invite Ruprecht to join them.
An Inquisitor comes to the convent to drive out the demons, with whom the nuns have been possessed since Renata’s arrival. During the rite of exorcism the bacchanalia starts. Some nuns call Renata a saint, the others almost get the Inquisitor ripped apart for he is a Satan’s minion. Mephistopheles takes Ruprecht to the convent to show him what has happened to Renata. She is condemned by the Inquisitor to be burned at the stake.