A London dock-worker becomes an opera singer and then traces his ancestors back to a West African island.
In 1700 a couple escape from cruel Queen Zinga (Cornelia Smith) on a West African island but are taken on a slave ship. A royal medallion is passed on to succeeding generations.
John Zinga (Paul Robeson) works at the docks and sings "Jericho." The opera composer Gabriel Donizetti (Esme Percy) hears him but loses him. John tells his wife Ruth Zinga (Elisabeth Welch) that he wonders about Africa and feels out of place in England. John sings "Down the River of Dreams" to her. Donizetti says that he must get the black singer, and he finds John at a saloon singing "Lonely Road." He offers John a career and instructs him how to sing. John agrees so that he can travel. In an opera he sings the role of an African king who shoots himself. Instead of speaking afterwards, John sings his "Freedom Song." The explorer Pyrie (Bernard Ansell) tells John that he heard that song somewhere, and he identifies the medallion with the island Kazanga. John tells Donizetti that he won't go to New York.
John and Ruby arrive at the island, and John says he is their king. They ask for a hut, and John calls it primitive. John visits the sick left for dead, orders water boiled, and gives them medicine. Mandingo (Ecce Homo Toto) helps John but says there can be no king. John breaks taboo and pushes down a magician (James Solomon). The man John treated died. John says what he can do. The magician challenges him and performs a rain dance. Monty (Robert Adams) offers John a gun, but he rejects it. Ruth frantically looks for women and is captured by the men. In jail Ruby sings "Down the River of Dreams." John is put in jail too, and Mandingo tells him that Ruth saw what is forbidden. John is taken bound to the king's chair to sentence Ruth. John says to let her go and sings his "Freedom Song." They call it the king's song and release Ruth. John returns to sing for Donizetti and makes money for his people. On stage John sings "Lonely Road."
Costumes in this film remind one of Marcus Garvey and the movement to return to Africa. Robeson's fine voice and humanitarian zeal are combined in this story of a man who returns to his roots and tries to help his people with the resources he gains from his singing career.