The plot is based on an old legend, retold with variations in such plays as Karl Vollmoller's Das Mirakel and Maurice Maeterlinck's Soeur Beatrice, and in the films Das Mirakel (1912), Milagro de amor (1946), and The Miracle (1959). Margarita is a nun, and the gatekeeper at her convent. Don Juan Alarcon, an unscrupulous adventurer, persuades her to run away with him and seduces her. Margarita eventually discovers that she is only one in a series of sexual conquests by Don Juan, and returns to the convent to find that her absence has not been noticed at all. The statue of the Virgin Mary in the convent chapel has come to life and has been taking her place. As Margarita prays for forgiveness, the statue returns to its pedestal. Meanwhile, Don Juan follows, and is miraculously struck down by heavenly lightning.