Joey Drayton brings her fiancé, Dr. John Prentice, home to sunny San Francisco to meet her affluent parents. Their liberal persuasions are now put to the test, for although the young man is an ideal choice (he's highly and internationally respected in the medical field, and he's impeccably mannered, handsome, well dressed and of a respectable California family), he's black. The film, which covers one busy day in the Drayton home, is essentially a drawing-room comedy, a series of cross-conversations between the young doctor and the girl's parents, and finally between all sets of parents and offspring. A simple dinner is extended to include the doctor's parents, who fly up from Los Angeles for the evening, and the crusty but benevolent old Irish priest, a friend of the family. Thus, the title of the film . . .

Detective Virgil Tibbs is caught up in the racial tension of the US South when he is arrested after the murder of a prominent businessman. Tibbs was simply waiting for his next train at the station in Sparta, Mississippi and the confusion is soon resolved but when local police chief Gillespie learns that Tibbs is the Philadelphia PD's number one homicide expert, he reluctantly asks for his assistance. The murdered man, Mr. Colbert, had come to Sparta from the North to build a new factory and his wife and business associates immediately point the finger at Endicott, the most powerful man in the county and the one who had the most to lose if a major new employer comes to the area. Tibbs' life is clearly in danger but he perseveres in a highly charged and racially explosive environment until the killer is found.