In a Catholic reformatory in 1914, three teenage girls (Anne, Theresa, and Lucy) pass the time with masturbation rituals, though they're innocent of the "sinful" nature of the act. Then a belligerent new girl, Joan, shows up, bearing illegal contraband: birth control materials distributed by the women's-rights activist Margaret Sanger. The girls start reading the material and jokingly pretend to venerate Sanger as a saint, but then they undergo a profound conversion experience. They begin to follow Sanger's life in the newspaper, pretending that they're traveling on their own, assassinating enemies and taking lovers at will. Through their letters to each other, they reveal their pasts, marked by abuse. The girls slide deeper and deeper into their illusion, to the extent that objects from their fantasy world start appearing in the real one -- including a baby.