TONIGHT'S MUST-SEE

"Big Brother All-Stars: America's Choice," 7 p.m., CBS. On a night with three major reality shows, CBS wins for the sheer size and audacity of its project.

Beginning July 6, its house will have a dozen people from previous seasons. First, however, voters decide who to put there.

Tonight, host Julie Chen introduce the 20 candidates. At midnight, viewers will have exactly a week to vote.

"Independent Lens: A Lion in the House," 9 p.m., PBS; concludes tomorrow. Painfully slow and deeply human, this documentary will move viewers. Some people will dislike its pace or its impact but admire its intentions.

Steven Bognar and Julia Reichert spent years filming young cancer patients and their families. In the first night, we meet Tim, 15, Alexandra, 7, and Justin, 19 and in his 10th year of leukemia.

Viewers will quickly respect the parents and medical people and will love the kids. That only makes "Lion" more painful to watch.

OF NOTE

"So You Think You Can Dance," 7 p.m., Fox. Reality shows have become so hot now that they have internal warfare. Nygel Lythgoe, an "Idol" producer, produces this show and is a judge; that puts him against his "Idol" colleague, Simon Cowell, whose new show (see below) premieres at 8. Tonight, 18 dancers perform. Viewers will trim that to 16 with the results announced Saturday.

"Freddie," 7:30 p.m., ABC. Freddie tries to revive his romance with Denise.

"America's Got Talent" debut, 8 p.m., NBC. Simon Cowell produces the show, which tries to go beyond his "American Idol." Instead of just pitting singers, it has everything — dancers, jugglers, comedians, goofy acts. One will win $1 million.

"Great Performances: Beyond the Steps —Alvin Ailey American Dance Theater," 8 p.m., PBS. Judith Jamison joined the Ailey company in 1965; she recalls a time of only eight dancers, in a shabby room. Now she has more than 30 dancers and a new, eight-story home. This documentary introduces the dancers, including a trip to Russia. Viewers will wish it included more dancing, but the bits shown are magnificent.

"Lost," 8 and 9 p.m., ABC. The first rerun is a superb episode focusing on Hurley's past and his present task — managing the food found inside the hatch. The second has Michael searching for Walt and Sun searching for her ring.

"AFI Life Achievement," 9 p.m., USA Network. Sean Connery is honored with an evening of memories and clips. Harrison Ford hosts a night that includes another past James Bond (Pierce Brosnan) and a future one (Daniel Craig), plus Steven Spielberg, Catherine Zeta-Jones, Mike Myers, Tom Jones, Eddie Izzard, James Earl Jones, Julia Ormond and more.