TONIGHT'S MUST-SEE

"Twitches," 8 and 9:45 p.m., Disney Channel. Imagine a 21st birthday surprise: You learn you have a twin and that you are both from an alternate universe. You have special powers and you really need them because forces are pursuing you. And ... well, it's a busy birthday. The Disney people, who are good at making Halloween movies, have come up with another one that kids and grown-ups can enjoy. Tia and Tamera Mowry really are twins, albeit not 21 (they're 27) and not, to our knowledge, from an alternate universe. In this show, they're opposites: One is rich and pampered, one is middle-class and diligent, both are startled by this whole alternate universe thing.

OF NOTE

"Haunting Sarah" (2005), 6 p.m., Lifetime. Kim Raver plays twins, only one of them currently alive

"Ghost Whisperer," 7 p.m., CBS. A young man refuses to go on to the next life until he learns who received his organ transplant.

"What I Like About You," 7 p.m., WB. Last season, this show had great fun pairing Jennie Garth and Jason Priestley, who were "Beverly Hills, 90210" cast mates. Now Priestley again guests on Garth's show; this starts a two-parter.

"Twins," 7:30 p.m., WB. Mitchee (Sara Gilbert), the smart twin, is tired of hearing people say she's not fun. She throws herself a birthday party. . If you're keeping track, that makes three shows about twins tonight.

"Reba," 8 p.m., WB. Reba agrees to take in a family left homeless by Hurricane Katrina then she learns this is more than she'd imagined.

"Threshold," 8 p.m., CBS. The team faces the possibility that the alien signal, which causes people to turn brutal, has been injected into the general mass media, where it can't be stopped.

"Hope & Faith," 8 p.m., ABC. Hope (Faith Ford) is so mad at Faith (Kelly Ripa) that she might not help her out of her various problems. That's serious, because Faith has lots of problems.

"Hot Properties," 8:30 p.m., ABC. The show's second episode, like its first, is way too broad for most tastes. The beautiful Lola is mourning the death of her pet chicken, so her friends start drinking. The next morning, they realize they've placed some ill-advised phone calls. One of the people who was called shows up at the door, causing fresh troubles.

"Numb3rs," 9 p.m., CBS. A key Wall Street witness has been shot before she can testify.