In the Heat of the Night (1968)

This is the movie that most likely inspired the television series of the same name.

Summary
-A Philadelphia homicide detective named Virgil Tibbs is asked to work alongside Chief William 'Bill' Gillespie in the sleepy, but racially hostile southern town of Sparta, Mississippi to investigate the murder of a prominent businessman

Cast
-Sidney Poitier: Virgil Tibbs
-Rod Steiger: Bill Gillespie
-Warren Oates: Sam Wood
-Lee Grant: Mrs. Colbert
-Larry Gates: Endicott
-James Patterson: Mr. Purdy
-William Schallert: Mayor Schubert
-Beah Richards: Mama Caleba
-Kermit Murdock: Henderson
-Quentin Dean: Delores

Did You Know?
-During filming, Sidney Poitier and Harry Belafonte were nearly killed by Ku Klux Klansmen during a visit to Mississippi. After that, they insisted the movie be filmed in the north. That gave way to the town of Sparta, Illinois. There were scenes that were filmed in Tennessee, such as exterior shots of cotton plantations because Illinois did not have them. Sidney Poitier slept with a gun under his pillow and received threats from local racist thugs. Production was shut down and moved to Illinois from that point on
-Despite the fact that the movie is set during summer in Mississippi, it was filmed during autumn in Illinois. The cast members chewed chips of ice but were asked to spit them out before filming began so their breath wouldn't be caught on film during the night scenes
-This is frequently cited as one of Sidney Poitier's top favorite film that he's done
-Because of Dr. Martin Luther King Jr. getting killed on April 4, 1968, the presentation for Best Picture Oscar for the film was postponed until April 10, 1968. It was originally supposed to be on April 8, 1968
-From what Sidney Poitier says, the scene where his character, Virgil Tibbs, slaps Endicott (Larry Gates), was not in the original script or even the novel it's based on. It was completely improvised and Poitier insisted that the scene be in the movie.
-Beah Richards, who played an abortionist named Mama Caleba, appeared with Sidney Poitier in Guess Who's Coming to Dinner. She played his mother in the film
-Despite the fact that Warren Oates and Lee Grant were among the top of the list for actors and actresses who play racist roles, they are very upfront about their support of the civil rights movement
-The N-word is used seven times, all directed toward Virgil Tibbs