TONIGHT'S MUST-SEE

"24," 8 p.m., Fox. Last week brought a pivotal moment with Jack Bauer finally working from the inside again. President Logan realized that one of his top aides had triggered a risky plan: Nerve gas would be stolen by terrorists then explode on their ship. The plan went terribly wrong: The bad guys prevented the explosion and are on the loose with 20 deadly canisters; a search begins.

"Surface," 7 p.m., NBC. Here's the final new episode for this season — and maybe forever — of this adventure about the discovery of an underwater scheme. Last week, Laura was almost killed, Rich was captured and young Miles was chased by an angry mob. That last part was set aside when word arrived that a tsunami was heading for Miles' hometown of Wilmington, N.C. Tonight, the evacuation begins, Laura searches for Rich and the various story lines entwine.

OF NOTE

"Skating With Celebrities," 7 p.m., Fox. Last week, Kurt Browning and Deborah Gibson were eliminated. That followed the previous dumping of Todd Bridges and Jenni Meno. Now four duos remain.

"For One Night," 7 p.m., Lifetime. Raven-Symone stars in this true story of a teen in Mercier, La., who fought the tradition of having segregated proms.

"How I Met Your Mother," 7:30 p.m., CBS. Ted and Victoria (Ashley Williams) are ready to quit abstaining from sex. They are so eager that they don't realize Marshall and Lily are in the apartment, too. Now Marshall and Lily feel they must hide in the bathroom.

"Two and a Half Men," 8 p.m., CBS. Again, abstaining is the subject. Charlie frets when it's time for him to have sex with Mia.

"The Bachelor: Paris," 8 p.m., ABC. Last week, Dr. Travis Stork, 33, trimmed the field to four. Tonight, he visits their families and hometowns. One woman (simply listed as Sarah S., 26) is a kindergarten teacher in Nashville, Tenn., the same town where he's an emergency-room doctor. Moana, 26, is a distribution manager from Los Angeles. Susan, 25, is a financial associate from Overland Park, Kan., and Sarah B., 23, is a student from Winnipeg, Canada.

"American Experience: Jesse James," 9 p.m., PBS. The Jesse James of legend was a skillful guerrilla fighter, working with other former Confederate soldiers to rob and kill. That much is true, this hour says, but he became increasingly solitary and bitter. It's an interesting story told with re-enactments that traces the life of the man shot to death at the age of 34.

"Courting Alex," 8:30 p.m., CBS. Alex obsesses on bad habits — her own, and a search for any that Scott might have.

"CSI: Miami," 9 p.m., CBS. Horatio is appalled when an alleged serial killer is dating the daughter of someone who may have been one of his victims.