TONIGHT'S MUST-SEE

"Lost," 8 p.m., ABC. OK, Sayid and Desmond did successfully reach the freighter. Now, however, they begin to learn what the ship's real mission is. Meanwhile, we're learning more about Juliet. In last week's episode (rerunning at 7 p.m.), she confronted someone from her past. This week, she shares a secret with Jin, because Sun is threatening to go over to Locke's side.

"In the Line of Fire" (1993), 5 and 11:45 p.m., AMC. Directed by Wolfgang Peterson ("The Perfect Storm"), "In the Line of Fire" features Clint Eastwood as a Secret Service agent haunted by his failure to protect President Kennedy. Now he's facing a crafty, would-be assassin (John Malkovich). This is a smartly written and directed thriller, with a great cast that also includes Rene Russo, John Mahoney and Fred Dalton Thompson — who, ironically, was a presidential candidate this year, with his own Secret Service protection.

OF NOTE

"Who Knew?" opener, 3 p.m., National Geographic Channel. Marshall Brain, author of "How Stuff Works," takes us on tours of factories. In tonight's first two segments, some viewers might be depressed to see robots replacing humans at such skills as painting a speedboat and test-hitting a golf ball; in the third, they'll be relieved to know that fireworks is an anti-automation business, with every detail done by hand. This film tries hard and tosses in some scattered information; we learn why golf balls have dimples and why fireworks buildings are small and soft-roofed. Still, much of this only seems a half-step above those industrial films that our teachers would show on their lazy days.

"Splash" (1984, WE/KHON, 451 digital), 5 p.m., and "Ice Age" (2002, FX), 3 p.m. Here are fun movies for kids or grown-ups. "Ice Age" is an animated tale of pre-historic beasts, rescuing a human baby; John Leguizamo voices many of the funniest lines. "Splash" had Ron Howard deftly directing a genial tale of a young man (Tom Hanks) and the mermaid he found (Daryl Hannah).

"My Name is Earl," 7 p.m., NBC. In the first rerun, the warden reneges on his promise of an early reunion, so Earl must fashion a jail break. In the second, he's free, penniless, angry at karma and returning to his bad ways. His brother plans an intervention. The real intervention, however, involves the arrival of a woman (Alyssa Milano) and a car.

"CSI: Crime Scene Investigation," 8 p.m., CBS. Lady Heather, Grissom's old friend, was attacked in an amusement park in this rerun but refuses to name the attacker. In another case, a pickpocket was hit by a car; Warrick and Nick try to determine if it was an accident.

"Celebrity Apprentice," 8 p.m., NBC. Each team must invent a new Quiznos sandwich and market it. Each gives the sandwich a celebrity identity and lures strangers from the sidewalk. One sells so many that it has to make more.

"Without a Trace," 9 p.m., CBS. A store Santa (yes, this is a rerun) disappears after getting death threats.

"Lipstick Jungle," 9:01 p.m., NBC. Wendy has a shot at landing a big movie deal for new characters being created by J.K. Rowling, the "Harry Potter" creator. She brings Nico — unaware that Nico is bringing along her young lover.

"Lil' Bush" season opener, 9:30 p.m., Comedy Central. An equal-opportunity offender, this cartoon series is now willing to take shots at both parties. It imagines a school attended by little George W. Bush and his pals — Rumsfeld, Cheney, Rice, Rove. The Little Dems are also there, led by Hillary Clinton, Barack Obama and a rather preachy Al Gore. Tonight, the Dems plan a St. Patrick's Day parade that is all-inclusive; Lil' Bush's gang plans a takeover. Both sides are mocked, in a satire that has some funny moments, but tends to be blunt and clumsy.