- Directors: Norman Jewison
- Producers: Walter Mirisch
- Writers: John Ball, Stirling Silliphant
- Genres: Drama, Mystery, Crime
- Actors: Sidney Poitier, Rod Steiger, Lee Grant
Colbert, a wealthy man from Chicago who was planning to build a factory in Sparta, Mississippi, is found murdered. Police Chief Bill Gillespie comes under pressure to quickly find his killer. A northerner Virgil Tibbs, passing through, is picked up at the train station with a substantial amount of cash in his wallet. Gillespie, heavily prejudiced against blacks, jumps to the conclusion he has his culprit, but is embarrassed to learn that Tibbs is a respected Philadelphia homicide detective who had been visiting his mother. After this racist treatment, Tibbs wants nothing more than to leave as quickly as possible even though his captain recommends he stay and help, but the victim’s widow is impressed by the detective’s expertise clearing another wrongly accused suspect of the crime and threatens to stop construction on the much-needed factory unless he leads the investigation. Gillespie then talks Tibbs into lending his services.
Despite the rocky start to their relationship, they come to respect each other as they are forced to work together to solve the crime. The suspects include Eric Endicott, a wealthy plantation owner who opposed the factory, diner counterman Ralph Henshaw and even police officer Sam Wood.
In the end, Tibbs discovers that Henshaw killed Colbert, with Henshaw doing so after Colbert picked him up as he hitchhiked to his graveyard shift at a local diner. Colbert was out driving around aimlessly after he left the hotel where he lived with his wife, unable to sleep. After picking up Henshaw, Colbert was asked, first, if he could provide Henshaw with a job at his factory, and, second, if he could point out its location. Colbert does so, and, while he and Henshaw are looking at the field in which the factory will be built, Henshaw picks up a wooden stake and strikes Colbert in the head with it. Colbert is killed, which was not Henshaw’s desire. He puts Colbert into his car, drives him into town (taking $600 of the $900 found in his wallet), and dumps him in an alley. He then heads to work as though nothing has happened. Henshaw needs the money, it turns out, to pay for the abortion of 16-year-old Delores Purdy. Tibbs ultimately discovers this need, and, in the climatic scene, confronts Henshaw when he arrives with Delores Purdy to pay for her abortion.