Adapted from Edgar Wallace's novel, a British officer lays down the law for two million Africans in Nigeria.
Commissioner Sanders (Leslie Banks) says Bosambo (Paul Robeson) is an escaped thief, and he has been acting as chief without Sanders' permission. Bosambo reports about warriors of the old king and says he will fight them although he did not start a war. Sanders recognizes Bosambo as a chief. King Mofolaba's warriors make slave raids along the river. Sanders sends a message by pigeon to Bosambo to stop the warriors and keep the men and women until he comes. Bosambo leads his warriors into battle by singing. Bosambo wins the battle and meets Lilongo (Nina Mae McKinney) among the captured women. At a palaver Sanders tells Mofolaba (Tony Wane) he will not allow slavery. Sanders sends the girls back to their parents, but Bosambo weds Lilongo. For Sanders Bosambo was a Christian, but for her he will be a Muslim.
After five years of peace and prosperity under Sanders, Bosambo initiates his son. Lilongo objects to his teaching him the killing dance. Sanders tells the chiefs to obey his replacement, Ferguson (Martin Walker). After drums pass the message that Sanders is dead, Father O'Leary (Allan Jeayes) tells Ferguson that two white men are illegally selling rifles and gin, and two churches were burned. Ferguson gives orders, and O'Leary wires for Sanders or four battalions. Ferguson, tied up, says Sanders will come. Mofolaba says Sanders is dead and kills Ferguson. Mofolaba's warriors do the lion dance.
Sanders in a plane flies over Africa and meets with Bosambo. Drums announce that Sanders is back with law. The white gun-seller shoots, is attacked, and is killed. Lilongo sings to her children; but warriors abduct her as bait. Sanders reprimands the chiefs for killing, stealing, and breaking laws. Bosambo sings, praising Sanders. While Sanders suffers from malaria, Bosambo finds Lilongo is gone. Bosambo sends his children to Sanders and goes alone to Mofolaba, offering 2,000 gold pieces for Lilongo; but he is captured. As they are about to be killed, Sanders attacks with guns. He asks who killed Ferguson and deposes Mofolaba. Sanders has Bosambo call the chiefs and his warriors. He makes Bosambo king, because he will treat all equally. Bosambo tells Sanders he learned the secret is to be loved, not feared, and he promises to keep the peace.
Paul Robeson was understandably upset by the portrayal of Africans as childish savages being taught about law by British imperialists with guns. The story reflects how British officers dominated African tribes without having much understanding of their cultures, though the lesson of rule by law is universal.