TONIGHT'S MUST-SEE

"Law & Order" season finale, 9 p.m., NBC. When the TV season started, Jeremy Sisto was playing a tough, free-lance expert on handling kidnappings. Sisto was great; the show (NBC's "Kidnapped") was so-so and soon faded. Now Sisto shows up to wrap up the "Law & Order" season. He's one of three major guest stars. Harry Hamlin ("L.A. Law") plays a prominent politician whose ex-wife has been brutally slain. He's a prime suspect — especially after he shows up alongside another body. At the trial, he has a slick and arrogant lawyer (Sisto) and a media-hungry judge, played by Jeffrey Tambor, who was the "Arrested Development" dad.

OF NOTE

"The Color Purple" (1985), 3 p.m., Oxygen. On a good night for movies, this is the one great film. Alice Walker's painful novel about mistreated women was stunning transplanted by master director Steven Spielberg. The pain is still there, but so is some immense visual and musical beauty.

"That's The Way It Is: Walter Cronkite at 90," 7 p.m., CBS. Life has changed in CBS and the world: Walter Cronkite went along with a CBS policy and retired as newscaster at 65; Bob Barker, by comparison, is retiring now at 83. Here's a documentary, profiling Cronkite some 25 years into retirement.

"House," 7 p.m., Fox. Michelle Trachtenberg, of "Buffy" fame, plays a teen heart-transplant recipient who suddenly faces a system shutdown. Meanwhile, Wilson and House are not doing well as temporary roommates.

"Painkiller Jane," 7 p.m., Sci Fi Channel. Psychiatric patients are all having the same nightmare. Jane suspects foul play.

"Gabon: The Last Eden," 7 p.m., National Geographic Channel. During the years when her father was a physician in Africa, Glenn Close developed a fondness for the continent. Here, she narrates a look at how Gabon (a Central African nation about the size of Colorado) has preserved a lush ecosystem. It is one of the few places, Geographic says, where someone can stand on a pristine beach and simultaneously see elephants, hippos and humpback whales. Further in, there are gorillas and mandrills in the continent's largest rain forest.

"National Bingo Night" debut, 8 p.m., ABC. Yes, bingo. In prime time, on network TV, with the audience watching or playing along. This may not be what people expected, in the Golden Age of TV drama.

"Dr. Phil: A Primetime Special: Caged," 8 p.m., CBS. Phil McGraw interviews the man accused of locking his 6-year-old son up and keeping him there for three years.

"Bones," 8 p.m., Fox. A skull has been found in the desert, where Angela and her boyfriend disappeared.

"Numb3rs" season finale, 9 p.m., CBS. A bomber is on a bridge, holding Don and Charlie to a standoff. Along the way, a key discovery is made.