Alexander recovers a story that has gone largely untold: how free and enslaved Black people in the United States moved to defend the young Caribbean republic against those determined to keep slavery and white supremacy intact. The arrival of a sovereign Black nation, the book argues, gave Black communities across the African diaspora a source of hope.

Placing Haiti at the center of Black internationalism's history, Alexander traces how the island's independence shaped Black thought and Black action in the United States. Haiti was what white society dreaded most, since it proved that a revolution by enslaved people could end in victory. Black activists responded by claiming a shared identity with Haitians and treating the two peoples' futures as one struggle. The book ties the revolution to a wider pursuit of liberation, justice, and social equality.

Between 1824 and 1826, some six thousand free black people left the United States for Hispaniola. Hidalgo works through archives in the Dominican Republic, Puerto Rico, the United Kingdom, and the United States to follow the philanthropic and missionary effort behind that migration.

Earlier writing has read the episode either as a chapter in Black Nationalism in the United States or as the origin story of the community that remained on the island. Hidalgo looks instead at the white participants and what happened to them as they crossed lines of race and culture.

Two figures carry the study. Loring Dewey organized the emigration against powerful opposition, and the archival trail suggests his sense of himself was shaken by what he saw of the emigrants' condition. William Cardy, a British missionary who lived among the settlers, went through something similar: personal crises loosened his attachment to home and drew him toward the people he had come to convert.