George Washington Black, known as “Wash,” is born enslaved on a Barbados sugar plantation where cruelty is the norm. When his master’s brother, Titch, arrives and chooses Wash to serve him, Wash is initially terrified; but the eccentric brother turns out to be a naturalist and abolitionist who takes Wash under his wing. A great deal of adventures follow, taking Wash from Barbados to Virginia, the Arctic, eventually London and further. The book moves, and the plot is by itself engrossing. But Edugyan doesn’t merely spin a good story: Wash’s fate is entangled with Titch’s in ways that interrogate not only the evils of slavery, but also the complex incentives in the movement to end it, and the contortions made by white families in its wake. At one point, Wash accuses Titch of abandoing him, and Titch responds that he “treated [him] like family”—a statement that is less a denial than a self-indictment. The closing paragraphs are among the most haunting I have ever read.