“The ‘convent exposé’ [was] a book, fictional or not, that purported to reveal the sin and salaciousness hidden behind the walls of religious institutions. In these books, sisters are kept captive, denied medical care, and sometimes raped or otherwise subject to sexual depravities. … These books, mostly forgotten today, were some of the most popular publications of their time.” (One was outsold onely by Uncle Tom’s Cabin.)