A Man of the People is told from the perspective of Odili Samalu, a young man in an unnamed African country. Though Odili's education level grooms him for privileged governmental jobs, he chooses to teach at a village school. After many years, Cultural Minister M.A. Nanga visits Anata, his home village and Odili's place of residence. Chief Nanga once taught Odili, and he immediately recognizes his former student during his visit. Although Odili is angry about the national government, he is quickly charmed by Chief Nanga's enthusiasm and charisma. It is revealed that Chief Nanga is considered by everyone to be the titular "man of the people." Despite Odili's personal politics, the teacher accepts Chief Nanga's invitation to stay at his home in the country's capital, Bori, for the holidays.
Upon his arrival at Chief Nanga's home, Odili discovers that his suspicions are true. Though Chief Nanga prides himself on his egalitarianism, he lives luxuriously and reaps the benefits of his corrupt governmental position. Ironically, Odili finds concrete evidence that Chief Nanga knows very little about his nation's culture. As Odili continues to narrate the story, he reveals the details of his upbringing and his past romances. He tells that audience that over the past few years, he has shared a relationship with Elsie, a young woman who is initially described as "beautiful" and "happy." While in Bori, Odili invites Elsie to Chief Nanga's home. One night, as Odili ascends the stairs to Elsie's room, he finds that Chief Nanga and Elsie are sleeping with one another. Devastated and angry, Odili begins to plot his revenge on the cultural minister. His plan has two parts: he decides to threaten Chief Nanga's personal life as well as his professional power. He vows to seduce Edna, Chief Nanga's fiancé, and he decides to run for office.
Odili reconnects with his old friend, Max, and his wife, Eunice, who are forming a new political party called the Common People's Convention (CPC). As Odili learns more about the corrupt government, he is prompted to involve himself politically. He makes the decision to run against Nanga during the election for Cultural Minister. Throughout his campaign, Odili is forced to consider his own morality. He is forced to grapple with the cynicism of the population he aims to represent and the pervasiveness of corruption. The safety of Odili's family is jeopardized during his campaign, and Odili is encouraged to take bribes and withdraw himself from the election. At one point in the story, Odili discovers that Max has taken a bribe from a minister named Chief Koko. Although Odili is angry at Max's opportunism, Max insists that the paper he signed has no legal importance and the money from the bribe will allow them to further fund their campaign. Meanwhile, Odili realizes that his pursuit of Edna is no longer fueled by vengeance or conquest. Odili wants to marry Edna, but she is afraid to leave Chief Nanga due to her family's financial investment in their marriage.
In the novel's climactic moment, Odili attends Chief Nanga's inaugural campaign meeting. While there, the Chief slanders Odili and explains how he is disappointed in his former student. Odili, intent on exposing Chief Nanga's corrupt behavior, takes to the microphone. However, before Odili can finish his opening sentence, he is slapped by Nanga and later ambushed by the entire crowd. He loses consciousness and wakes up in a hospital bed. During his recovery, Odili discovers that he has lost the election and that Max has been killed by Koko. Eunice seeks revenge for her husband's death and murders Koko. Although Chief Nanga's party has won the election, his victory is short-lived. The military stages a coup d'état, and Nanga is arrested. Max is declared a martyr and a revolutionary hero. With Chief Nanga in jail, Odili and Edna reunite and decide to marry.
