TONIGHT'S MUST-SEES

"American Idol," 7 p.m., Fox. There are only three hours left of chaotic auditions. The show's new plan spends less time gawking at these oddities. That will provide an extra week to personalize people who reach the next round. Tonight through Thursday, we get the last audition hours. Then it's on to the Hollywood round and (mostly) people who can sing.

"Nova: The Incredible Journey of the Butterflies," 8 p.m., PBS. Each year, millions of monarch butterflies leave their homes in Canada or the Northern U.S. They begin a two-month, 2,000-mile trip to a mountainous section of Central Mexico. Often, a butterfly must cross the Great Lakes without landmarks. "It's moving South," says Chip Taylor of the University of Kansas. "Somehow, it finds its way to Mexico. Could you do that?" Taylor even tried to confuse the butterflies, letting them loose in Washington, D.C. At first, they headed due South; somehow, they corrected themselves and reached their traditional spot. This hour is filled with gorgeous footage, some of it shot by helicopter and hot-air balloon. It also catches the human side. In Michoacan, villagers focus on this phenomenon for much of their income. They create art work, rent rooms, hold a festival.

OF NOTE

"The Devil Wears Prada" (2006), 5:30 p.m., FX. Here's another chance to catch this witty drama-comedy. Anne Hathaway plays the wide-eyed assistant to an unyielding boss (Merle Streep); David Frankel directed, giving a slick, cosmopolitan look.

"NCIS," 7 p.m., CBS. A sergeant who was killed may have committed treason.

"The Mentalist," 8 p.m., CBS. In a rerun, Patrick Jane — a former fake psychic — wants to trap a current fake, by pretending to set up a seance. It's a double night for Simon Baker, who stars here and has a supporting role in "Prada."

"The Whitest Kids U Know" season-opener, 8 and 11 p.m., IFC. These guys are at their best when creating clueless sorts, in the "Wayne's World" mode. Forgive tonight's so-so opening sketch, involving Hitler and Charlie Chaplin. It's followed by home-made videos of Bible stories. And used-car commercials by the owner's wildly disinterested sons. Best of all is a public-access newscast done shortly after aliens have abducted all the smart people; Wayne and Garth would love this one.

"Fringe," 8:01 p.m., Fox. A killer is turning people's brains into liquid. Someone Olivia knows may be the next victim.

"Frontline/World" season-opener, 9 p.m., PBS. One scheduled report involves shop-owners who resisted the Sicilian Mafia; another views Muslims from small-town China who were confined in Guantanamo Bay. Also, we meet a Brazilian politician who changed his name to Barack Obama before running for mayor.

"10 Items or Less," 9 p.m., TBS. Tonight's episode reminds us that it's dangerous to have a seductive woman in a halter top near someone performing delicate eye surgery. The results are messy, in an episode that is sometimes overwrought, but has its funny moments.

"Law & Order: Special Victims Unit," 9 p.m., NBC. In a rerun, James Brolin guests as an astronaut, helping investigate the death of a famous astronaut.