Set in the fictional Yoknapatawpha County, Intruder in the Dust revolves around a murder trial and its aftermath in the small, racially tense town of Mississippi. The plot centers on Lucas Beauchamp, an African American man who has been accused of murdering a white man, Vincent Keyes. Despite Beauchamp's insistence on his innocence, he is imprisoned, and the local community is divided by racial prejudice and class tensions.

The story is told from the perspective of Charles Mallison, a young white boy who is the nephew of the novel's protagonist, Mississippi's old attorney Aunt Alex, and their investigation into the circumstances of the crime. Through this investigation, Charles comes to realize that the case is not as clear-cut as it appears, and the novel explores themes of justice, racial inequality, and moral courage.

The title Intruder in the Dust alludes to the outsider figure of Beauchamp, a man whose arrival shakes the town's foundation and whose case forces everyone to confront uncomfortable truths about race and societal expectations. Faulkner deftly examines the tension between justice and racial prejudice and underscores the power of empathy and human connection in the face of a broken system.