While traveling in the deep south, Vigil Tibbs, a black Philadelphia homicide detective, becomes unwittingly embroiled in the murder investigation of a prominent businessman when he is first accused of the crime -- and then asked to solve it! Finding the killer proves to be difficult, however, especially when his efforts are constantly thwarted by the bigoted town Sheriff (Steiger). But neither man can solve this case alone. Putting aside their differences and prejudices, they join forces in a desperate race against time to discover the shocking truth.