TONIGHT'S MUST-SEE

"American Masters: George Gershwin: Remembered," 9 p.m., PBS. George Gershwin seemed to absorb all the forces of a vibrant society. The son of Jewish immigrants, he grew up in a Brooklyn filled with new Americans. He wrote for Broadway and Hollywood. He did light pop, complex jazz, even classical music. He blended them all together, doing some of his best work in an opera ("Porgy and Bess") filled with black dialect. He did it all, then died of a brain tumor at 38. His story is richly captured in this documentary, which includes clips from Judy Garland, Gene Kelly and the "Porgy" cast. Celebrating its 20th anniversary, "American Masters" is doing what PBS doesn't do enough — bringing back great moments. This month, the show's emphasis is on songwriting genius, with Gershwin tonight, Cole Porter on June 14, and Bob Dylan on June 28 and July 5.

OF NOTE

"Gameshow Marathon," 7 p.m., CBS. Tonight, the celebrities — well semi-celebrities — try Beat the Clock.

"The George Lopez Show," 7 p.m., ABC. George decides he should inspire his son by taking some college classes.

"Freddie," 7:30 p.m., ABC. Freddie and Chris are both in the running to be named Chicago's top bachelor. Both really want the honor — and a spot on a magazine cover.

"Lost," 8 p.m., ABC. Inside the hatch in this rerun, Locke, Kate and Jack face a dangerous figure; also, Locke begins working with the odd demands of the hatch numbers. Meanwhile, the rafters face their own dangers. We also get flashbacks that show Michael's break-up.

"Law & Order," 8 and 9 p.m., NBC. The first episode has a teen runaway killed by his suburbanite mom. The second has a man killed after he defiled a treasured Torah.

"So You Think You Can Dance," 8 p.m., Fox. It's time for a new round of Las Vegas auditions, featuring people who got callbacks.

"CSI: NY," 9 p.m., CBS. An assistant district attorney is found dead in a cemetery, but there's no sign of the bullet. It turns out that some dangerous game playing was involved.

"Commander in Chief," 9 p.m., ABC. In a new episode, a hostage crisis breaks out in Turkey. Mac faces that while juggling political concerns as she chooses a vice president.