Photo Gallery
Of course it turns out that Poitier's Virgil Tibbs is also a police detective, and in one of cinema's least logical plot twists, he is asked by his supervisors back home to pitch in with the murder investigation. All sides are reluctant, at least until the crime is ultimately solved and everyone comes to understand a bit about the other side of the fence. (How that got Tibbs to stick around in redneck central for two sequels and eight years as a TV show is never really explained.)
In the Heat of the Night is far -- far -- more interested in racial politics than criminal capers, and it's Tibbs' interactions with the local yokels that make the film so memorable. Poitier's bellowing of the classic line, 'They call me Mister Tibbs!' resounds so fully that it actually became the title of the first sequel to the film. Steiger won the Best Actor Oscar (which is hard to justify vs. Poitier's work, which is considerably better), and the film won Best Picture (equally hard to justify over nominees Bonnie and Clyde and The Graduate). But that's politics for ya.
A 40th anniversary DVD adds commentary by Jewison, Steiger, lenser Haskell Wexler, and Lee Grant.