Impressive in his first major film role, Will Smith plays a young con man posing as Sidney Poitier’s son. But the film belongs to Stockard Channing, as an Upper East Side socialite and art collector (with Donald Sutherland playing her husband). She reprises her Broadway role in John Guare’s best-known play to give her finest screen performance. The film version retains the essence of the play while making it wonderfully cinematic.