I read quite a bit about the Grimke sisters in graduate school while studying nineteenth-century women's rhetoric (including both Sarah's treatise on the equality of the sexes and Angelina's letter to the Christian ministers of the South), so I was fascinated to find that Kidd had built her latest novel around their lives.
Although there were places where the pacing dragged a little for me, I thought Kidd did a nice job of presenting two distinct experiences with slavery: Sarah Grimke, who grew up benefiting from the practice but who resisted it (though she spends a long time trying to figure out how to shape that resistance), and Handful, one of her family's slaves. I liked that Handful never let slavery define her, and she did what she could to resist it (though her actual involvement with Denmark Vesey seemed a bit of a stretch--she also seemed to have an unusual amount of freedom to visit Charleston).
But I was more drawn to Sarah, mostly because I could relate to her struggle with knowing something is wrong but trying to figure out how to resist it. Sarah was a slow-blossoming character who didn't come into her own until her thirties--and I felt like that was a much more realistic approach than what I sometimes see, which is characters who immediately see injustice and know instinctively how to respond to it. I appreciated that Kidd focused her attention on the lesser-known of the two sisters, because I think Sarah has an equally interesting story (if not as flamboyant--if you haven't read Angelina's speech at Pennsylvania Hall, you should).