In the early 1830s, Sarah Grimké and her younger sister, Angelina, were the most infamous women in America. They had rebelled so vocally against their family, society, and their religion that they were reviled, pursued, and exiled from their home city of Charleston, South Carolina, under threat of death. Their crime was speaking out in favor of liberty and equality and for African American slaves and women, arguments too radically humanist even for the abolitionists of their time. Their lectures drew crowds of thousands, even (shockingly, then) men, and their most popular pamphlet directly inspired Harriet Beecher Stowe’s Uncle Tom's Cabin--published 15 years later. These women took many of the first brutal backlashes against feminists and abolitionists, but even their names are barely known now. Sue Monk Kidd became fascinated by these sisters, and the question of what compelled them to risk certain fury and say with the full force of their convictions what others had not (or could not). She discovered that in 1803, when Sarah turned 11, her parents gave her the “human present” of 10-year-old Hetty to be her handmaid, and Sarah taught Hetty to read, an act of rebellion met wit...