In 1927, eighteen-year-old Mary Engle is hired as a secretary at the remote institution for mentally disabled women called the Nettleton State Village for Feebleminded Women of Childbearing Age. She soon comes to admire how dedicated the director, Dr. Agnes Vogel, is to the poor and vulnerable women under her care, but she discovers that a childhood friend of hers is an inmate and not all is as it seems.