Today on TV

NBA playoffs: Magic at Celtics (6 p.m., TNT): Rockets at Lakers (8:30 p.m., TNT)

NCIS (7 p.m., Ch. 2): A security breach kills an ICE agent.

Biggest Loser (7 p.m., Ch. 5): Winners are declared in this three-hour — yes, three-hour — finale.

American Idol (7 p.m., Ch. 13): The three remaining contestants — Kris Allen, Danny Gokey and Adam Lambert — perform.

Reaper (7 p.m., Ch. 30): Sam has to send his high school chemistry teacher back to hell.

The Mentalist (8 p.m., Ch. 2): A student in a program for troubled kids is murdered.

Dancing With the Stars (8 p.m., Ch. 4): Another couple is eliminated.

Fringe (8:04 p.m., Ch. 13): We're promised that questions will be answered in the first-season finale. But not all questions, obviously, because Fox has ordered a second season. And "Star Trek's" original Mr. Spock, Leonard Nimoy, makes a guest appearance.

Without a Trace (9:01 p.m., Ch. 2): The boyfriend of Jack's daughter runs away.

Cupid (9:02 p.m., Ch. 4): Trevor tries to bring together a radio disc jockey and one of his listeners.

Frontline (9 p.m., Ch. 7): A report on Bernie Madoff's ponzi scheme.

Rescue Me (11 p.m., FX): Tommy returns to Ground Zero.

Independent Lens (11 p.m., Ch. 7): Gangs are the focus of "Crips and Bloods: Made in America."