The Restless Crucible narrates the story of Pedro de Barbosa, a Brazilian ex-slave now turned slave merchant, who must go up against Queen Ena Sunu, the powerful Dahomeyan monarch resolved to end slave traffic in her kingdom. Set in late 18th- and early 19th-Century Salvador da Bahia, Brazil, and Dahomey on the West African coast, the novel describes Pedro de Barbosa's fight to become free in the Brazil of his time, as well as the events and actions that lead him to engage in the abominable yet lucrative slave trade.

At the heart of this trajectory are the conditions that condemn an individual to poverty, discrimination, and humiliation because of skin color. The project to insulate himself from these injustices leads to a confrontation with the Dahomeyan Queen Ena Sunu, whose personal story of forced marriage to the Dahomeyan King, and the negation of her agency as a female in this tradition-bound society, brings an uncomfortable identification with the enemy and the need to protect her society from both local and foreign predators. Queen Ena Sunu's misgivings are confirmed when her husband, along with the Portuguese Governor and the king of Ouidah, deposes her father and sells him and his royal family into bondage. Queen Ena Sunu resolves to thwart the slave business in Dahomey and Ouidah, bringing up a long-delayed showdown with Pedro de Barbosa.