TONIGHT'S MUST-SEE

"Heroes," 8 p.m., NBC. As the new season began, viewers were baffled. Nathan and Peter had soared into the sky, where there was a nuclear fireball. But now Nathan seemed barely harmed; Peter was in another part of the world, with no memory. What happened? Now we get a flashback that covers the four months between seasons. There's a serene phase for Niki, D.L and Micah. There's the horrific start to Maya's nightmare. There's a visit inside The Company, meeting someone from the distant past. Some of this — Maya's story, the brothers' survival — is overblown, some is superb. Best is Elle, the warm and vengeful child-woman, brilliantly played by Kristin Bell.

"Billy Crystal: The Kennedy Center Mark Twain Prize," 9 p.m., PBS. These 90 minutes are stuffed with funny clips and funny people. A few guests are too doting, but most — from Robin Williams to Bob Costas to Crystal himself — are terrific.

OF NOTE

"Chuck," 7 p.m., NBC. Chuck is torn between his fake romance with a CIA agent and a real one with a beauty, played by Rachel Bilson.

"Prison Break," 7 p.m., Fox. Michael has four days to sneak Whistler away.

"How I Met Your Mother," 7 p.m., CBS. People seem to find varying faults in Ted's new girlfriend — often revealing more about themselves.

"Big Bang Theory," 7:30 p.m., CBS. Reluctantly going on a blind date, Koothrappali learns he can talk to women — if he's had alcohol.

"Two and a Half Men," 8 p.m., CBS. With Charlie's jingles-writing career fading, he's been working on children's songs. Now he may have a new career, singing for kids.

"K-Ville," 8 p.m., Fox. Cobb goes undercover, working with his old criminal friends.

"Murder by the Book," 8 p.m., Court TV. When three young Starbucks workers were killed in upper-income Georgetown, police were perplexed. No money was taken, and the workers had no reason to have enemies. This story is introduced by author David Baldacci, but has few of the twists of crime fiction. It's still interesting, though, including some daring moments by the police.

"Samantha Who?" 8:30 p.m., ABC. Samantha is starting to realize she has a shaky past. A former boyfriend has a restraining order against her.

"The Bachelor," 9 p.m., ABC. Next week, we learn whether Brad chose DeAnna or Jenni. First, however, the other women get their say.