TONIGHT'S MUST-SEE

"Amazing Race 12" season-opener, 7 p.m., CBS. CBS had this Emmy-winner on its shelf and the lunk-headed "Viva Laughlin" on its schedule. Now sanity returns, and "Viva" is gone. The new "Amazing" line-up has four dating couples, including two Goths, ages 31 and 29. The only married team has lesbian Episcopal ministers, 65 and 49. There's a brother-sister, a sister-sister and two sets of friends. And there are generation gaps — a father-daughter, 58 and 26, and a grandfather and grandson, 68 and 23. The race begins in Beverly Hills, at the Playboy Mansion.

"Desperate Housewives," 8 p.m., ABC. Last week's episode settled key issues: Danielle will keep a convertible, not the baby. Carlos and Gabrielle won't sneak off until they shed their current mates. And Katherine has to be nice for a while. It seems the new gay neighbors know about her husband's old Chicago trouble. With things in balance, it's time for a Halloween party. In the midst of it come surprises for Edie and Mike.

OF NOTE

"Dexter," 7 p.m., Showtime. A copycat killer inspired by the Bay Harbor Butcher brings competition for Dexter, who finds himself attracted to Lila.

"Masterpiece Theatre: The Amazing Mrs. Pritchard," 8 p.m., PBS. In the mid-section of an excellent, five-week miniseries, a former supermarket manager (Jane Horrocks) has almost adjusted to being prime minister. Then a plane crash suggests terrorism and one of her top people becomes a messy drunk. It's another strong hour with great moments from Jodhi May as her communications chief.

"Cold Case," 8 p.m., CBS. The show's 100th episode looks back to 1938 when a radio show made people thing Martians were attacking. At the time, a woman was listed as missing; now the case is re-opened.

"The Shot" debut, 8 p.m., VH1. There's some fun and glamour here when 10 photographers compete by shooting exotic photos. Still, photographer Russell James — the host and judge — has trouble explaining his logic. And why send people out on a sea shoot without some warning so they can take motion-sickness pills?

"Shark," 9 p.m., CBS. Stark really isn't supposed to be a bounty hunter. Tonight, however, he and Danny head to Mexico to retrieve a suspect. Guest stars include Brenda Strong (the voice of "Desperate Housewives") and Meredith Monroe ("Dawson's Creek").