An unnamed group of three civil rights activists in Mississippi go suddenly missing. Two of them were Jewish, and the third was African American. Already, it seems fairly obvious that the intentions of whomever vanished them were to show the world that they did not like minorities, but in a town where everyone feels this way, it is hard to identify a suspect. Alan Ward and Rupert Anderson, a former Mississippi Sheriff, learn this the hard way when they begin to interview the local townspeople.
The Sheriff of the town where the incident occurred (in 1964) is Ray Stuckey, who the two detectives quickly learn in tied to the Ku Klux Klan. Mrs. Pell, the wife of the Deputy Sheriff of the community, seems to be the only one to take the investigation seriously. She informs the men that the group of three was murdered, and they later find their bodies hidden. The Sheriff tells Mr. Pell that his wife betrayed their side, and Pell beats her.
The FBI arranges that Mayor Tilman of the community be abducted, without his knowledge, of course. He is placed in a shed with an African American man, who he believes to be insane. The man threatens to castrate Tilman if he does not tell him about the crime - Tilman eventually gives in. Because of Tilman's suspicion of people of different ethnicities, he ignores the fact that this man may have been sent to do this, and genuinely believes his threats.
Lester Cowens is a member of the Klan that the FBI decides to interrogate next. One day, he is at home and finds a burning cross in his yard, a sure sign that the Klan is after him. Unsure what they want with him, he attempts to escape via his truck, but is told by the FBI that this was all staged to try to get him to tell the truth about the murder.
At the end of the film, the people are still brutally divided - Mrs. Pell leaves her husband to seek more freedom, and the FBI searches are inconclusive. Alan and Rupert visit an African American cemetery and read a gravestone engraved with "Not Forgotten".
