TONIGHT'S MUST-SEE

"Heroes," 8 p.m., NBC. Last week brought thunder-shocks for Hiro (Masi Oka). Propelled into New York City a month in the future, he was accused of murder. He also witnessed a nuclear explosion. Now he's back in Japan, in the present, with a challenge. Can he convince a colleague that he's seen the future and it must be altered? Meanwhile, teen Claire (Hayden Panettiere) tries futilely to be normal, politician Nathan (Adrian Pasdar) schemes, and troubled Niki (Ali Larter) takes orders from a stranger. Also, many people separately chase a serial killer.

"What About Brian" season-opener, 9 p.m., ABC. Last season ended with Brian still wildly in love with his best friend's fiancee. The only solution, he's decided, is to stay away until after the wedding. That plan vanishes in a spectacular moment, and new crises appear. We're reminded of this show's flaw. Beautifully acted and filmed, it's still built around tortured relationships that can't hold our interest week after week.

OF NOTE

Baseball, 2 p.m., Fox. This is supposed to be the final game of the Dodgers-Mets or Cardinals-Padres play-offs. If neither one needs a fifth game, Fox will plug in reruns of "Prison Break."

"Egypt: Engineering an Empire" debut, 6 p.m., History Channel. Some 5,000 years ago, with no computers or cranes or power tools, the Egyptians created awesome structures. This richly filmed series investigates how they did it.

"How I Met Your Mother," 7 p.m., CBS. This show has switched slots with "The Class." Tonight, Ted and Robin have their first fight.

"The Class," 7:30 p.m., CBS. Nicole squirms as her husband and her would-be lover become pals.

"Two and a Half Men," 8 p.m., CBS. Here's bad news for Alan: His estranged wife Kandi has hired the same tough lawyer who worked for ex-wife Judith.

"The New Adventures of Old Christine," 8:30 p.m., CBS. When her ex-husband takes her son to church, Christine must confront her own dread of religion.

"American Experience: Eyes on the Prize," 9 p.m., PBS. Here's the mid-section of this brilliant, 1987 documentary series, airing over three Mondays, on the civil rights era. This portion is 1961-63, ranging from the lunch-counter sit-in in Greensboro, N.C., to Martin Luther King's "I Have a Dream" speech.

"CSI: Miami," 9 p.m., CBS. It's pretty-guy time. Two male models are killed; Rob Estes arrives as Natalia's abusive ex-husband.

"Studio 60 on the Sunset Strip," 9 p.m., NBC. In real life, Jay Mohr said he once stole a bit from a comedian and performed it as his own on "Saturday Night Live." Here's a fictional version: Learning that a sketch has been plagiarized, producers try to pull it from the West Coast telecast, which starts three hours after the East Coast one.