Writer/director Tom Ross' perennial holiday show at the Marsh (now in its eighth year) provides a lot of pleasure in its own small, dopey way. The Carpenters' bland songs never did much for me: Richard's immaculate production and Karen's smoothly modulated vocals were like steel cages, ensuring that no messy emotion ever escaped. But Katie Guthorn as Karen is a true star. A terrific singer, she nearly turns "Rainy Days and Mondays" into a good song. Her purposefully affectless speaking voice succeeds at conveying a lonely, unhappy woman, even as it makes you laugh. Karen overnarrates her own life ("And then I heard someone knocking," she states after someone knocks), and her melancholy never really leaves her. She doesn't understand her rapport with an audience. ("Sing along if you know the word!" she exhorts at the end of "Close to You." The word, of course, is "Wah-ahah-ahh," followed by the song's title.) The references to Karen's lack of appetite are funny and sad. The show's conceit is that while planning the Carpenters' Christmas variety special, Karen confesses she's in a funk. Her wan brother, Richard (Morey Goldstein), isn't much help, but she's visited by the spirits both of Christmases past -- Alvin the Chipmunk (Joshua Raoul Brody and a hand puppet) -- and Christmas present -- Barbra Streisand (an energetic Jo-Carol). They buck her up, and the show proceeds, with guest appearances by Ethel Merman (Jo-Carol again, singing "There's No Christmas Like This Christmas") and Tom Jones (Steffanos X in ruffles and velvet bell-bottoms). There are some clunky moments, and in two instances, the singers aren't miked when they should be (Jones singing "It's Not Unusual" and Babs and Karen dueting on "Enough Is Enough"). But the show has heart, and that's something the Carpenters never had before.