15-year-old Mary Rosalia (Susan Hemingway Susan Hemingway) is seen by Father Vincent (William Berg William Berger) accused of debauchery and infidelity for playing with her fianc é Cristo in the suburbs. Threatened by Vincent, Mary's mother (Patricia Da Silva) is forced to donate her savings and send her daughter to the Cerrard Aris monastery. The monastery appeared to be forbidden to be pious. Mary entered the monastery not only to examine her virginity, but also to talk about her sins, and continued austerity and prayer for three days. However, the so-called piety seems to be an illusion, with the nuns secretly worshipping the devil Satan (Herbert Fox Herbert Fux) and performing evil and wild rituals. Mary tried to escape, but she was snitched and faced a severe trial. Suffering physically and mentally, Mary had to write to the Supreme God.