Rutherford Calhoun is a freed slave, but he lives in debt to a man named Papa Zeringue. A woman named Isadora Bailey offers to pay the entire debt in exchange for Calhoun's hand in marriage, but Calhoun is really just not interested in her or in settling in the south. He finds a voyage from a ship cook in port, and he flees from New Orleans, LA on a vessel call the "Republic" as a stowaway.
On the ship, he is discovered and he is told he must work on the ship as a slave. He works for his keep, and the voyage turns out to be a slaving vessel. On the coast of Africa, the captain, Ebenezer Falcon, abducts Allmuseri people from Africa to be slaves in America. He also buys their sacred animal that represents the Allmuseri god, and the ship becomes nervous, wondering if the slaves can curse them for stealing the god. Sure enough, the ship ends up in a storm and they all almost die. The sailors blame Falcon's sacrilige for the storm, and they decide they will mutiny.
But then the Allmuseri escape from their cargo cells, and suddenly, Calhoun steps forward. He explains that if they can work together, they can survive, but if they fight, they will die. Falcon sees he is no longer in control and he kills himself. His second-in-command is inept, and soon, Calhoun becomes captain, but not before he visits the sacred animal in the hull. The mystical creature gives him a religious epiphany where he learns the future.
The storm nearly destroyed the ship, and without a full staff to run it, the ship deteriorates further. As if sinks, another vessel, the "Juno" comes and rescues the survivors. Isadora happens to be aboard, and she is marrying Zeringue. When Zeringue sees that he is being implicated in the illegal slave trade. They strike a deal, and Zeringue frees his slave and his fiancee, Isadora decides that this time, she will not mess things up, and Isadora and Calhoun are married. They return to America.
