TONIGHT'S MUST-SEE

"The Office," 7 and 7:30 p.m., TBS. If you missed the early days of this Emmy-winning comedy, it's time to catch up. TBS starts with the first two episodes. The first has Michael (Steve Carell) introduce his office to a film crew. It's fairly funny, but the second is much better. An expert (played by Larry Wilmore, one of the show's producers) arrives to teach diversity. Michael promptly botches things in lunk-headed (and hilarious) ways.

"Biggest Loser" season opener, 7 p.m., NBC. Alison Sweeney — who says she had weight problems as a teen soap star — takes over as host, with 18 contestants. They range from a cowboy to three teachers and a Hurricane Katrina survivor. There are twins (a salesman and a cop), a 21-year-old singer, a 62-year-old retiree and more. This episode tells six of them they've been dumped — then moves them to a secret project. It's a cruel step, in an otherwise well-meaning show.

OF NOTE

Documentaries about Sept. 11, 5 a.m., History Channel. Here's a 14-hour block on the World Trade Center attacks, six years ago today.

"Pinochet's Last Stand," 6 p.m., HBO. After he was arrested for crimes against humanity, Chilean dictator Augusto Pinochet spent 500 days under house arrest with his wife, in a golfing community in suburban London. Derek Jacobi stars in this account.

"Nova: Building on Ground Zero," 8 p.m., PBS. This rerun calmly looks at why the World Trade Center towers collapsed and what could be done in the future.

"Lincoln Heights," 8 p.m., ABC Family. In last week's season opener, riots broke out at school and Eddie, the cop, was shot. Now he's recovering at home and giving orders.

"House," 8 p.m., Fox. You don't expect violence to break out at a chess match. When that happens, Dr. House has one of his most intriguing patients.

"NCIS," 9 p.m., CBS. Gibbs is made acting chief in this rerun, but he doesn't want to be deskbound. He takes the staff to probe the murder of a woman who was heading to the NCIS headquarters.