TONIGHT'S MUST-SEE

"24" season finale, 7 p.m., Fox. Jack Bauer (Kiefer Sutherland) wraps up his fifth chance to save the world. As usual, the world is in precarious shape. For a time, the evil Bierko (Julian Sands) had been captured and the nerve gas canisters seemed to be recovered. He escaped — people do that on this show — and grabbed his back-up canister. He used it to get control of a nuclear submarine. Now Jack races to stop him, reluctantly bringing Henderson (Peter Weller), who knows the weapons system on the sub. There are more complications. People want to kill Jack. First lady Martha Logan (Jean Smart) has killed a federal agent who was about to kill Pierce. There's much more going on but just settle back and try it. "24" has been consistently well-made.

OF NOTE

"The New Adventures of Old Christine," 7:30 and 8:30 p.m., CBS. This midyear comedy has been a pleasant surprise and will be back next season. First, it offers its last two new episodes of the current bunch. In one, Christine figures she's finally found a friend at her son's upscale school; then she has her doubts. In the second, she bumps into Burton, the ideal boyfriend she inexplicably dumped. He has a new girlfriend who is, of course, also named Christine. Romantic aftershocks follow.

"Two and a Half Men," 8 p.m., CBS. Last week, Mia, the ballet dancer, returned. She simply wanted Charlie to donate sperm. He surprised everyone — including himself — by proposing.

"American Experience: The Man Behind Hitler," 9 p.m., PBS. As dark and hateful a 90 minutes as you'll encounter on TV. The words are from Joseph Goebbels' diary, as read by Kenneth Branagh. Old footage that is painful but important.

"The Medium," 9 p.m., NBC. In a dream, Allison sees herself as a high-powered attorney who's not married to Jake.