TONIGHT'S MUST-SEE

"Planet in Peril," 3 p.m., CNN; concludes tomorrow. Let's credit CNN for scope and diligence. Its passionate reporters went to 13 countries on four continents. Jeff Corwin visited Alaska, where the polar bear is losing its habitat. Anderson Cooper was in Greenland, viewing an island that was discovered when the ice sheet melted. Both were in Brazil, where the "poacher police" raid illegal logging camps. Dr. Sanjay Gupta was in China, where endangered species are noted on an alternate menu. And in Central Africa, where a massive lake is drying up. In the portions we saw, the filming style is fairly stiff. The subjects, however, are crucial.

"House," 8 p.m., Fox. After a seizure, a young funeral-home worker thinks she sees corpses moving. She also chats with her late mother. Now House's research goes to the cemetery and beyond.

OF NOTE

Horror films, all night. On the nasty side is "Saw" (2004), at 4:30 p.m. on Sci Fi; it's a tense tale of captivity and torture. On the moderate side is the comedy-drama "The Frighteners" (1996), at 8 p.m. on ABC Family; before making "Lord of the Rings," Peter Jackson directed this tale, with Michael J. Fox probing the paranormal.

"Bones," 7 p.m., Fox. A supermarket magnate has been killed, with possible motives ranging from business to romance. Meanwhile, Booth and Brennan have an extremely young psychiatrist; he's played by John Francis Daley, 22, best-known for "Freaks and Geeks."

"Damages," 7 p.m., FX. This perplexing and interesting series wraps up its first season. A young lawyer finds herself trapped between the schemes of her own hard-driving boss (Glenn Close) and their opponent (Ted Danson).

"The Unit," 8 p.m., CBS. A chip identifies three men working undercover. The team scrambles to get it back.

"Boston Legal," 9 p.m., ABC. Alan is unsettled by a woman who wants advice on killing her daughter's killer.

"Frontline: Showdown With Iran," 9 p.m., PBS. Before the U.S. invaded Iraq, this documentary says, it received overtures from Iran, calling for a bargain. Instead, it took a confrontational approach. Now that two neighbors (Iraq and Afghanistan) have been neutralized, Iran seems stronger than ever.

"Independent Lens: Vote For Me," 10 p.m., PBS. This new notion of democracy causes a stir in China. Here, teachers have nominated three 8-year-olds for class monitor. The kids take it casually, but their parents want them to push hard. That's captured in a low-key and charming documentary.