When Secrets Kill (Sun. (6), 9-11 p.m., ABC) Filmed in Canada by Scripps Howard Entertainment, Michele Brustin Prod., Rysher Entertainment. Executive producers, Michele Brustin, Richard Brams; co-executive producer, Kimberly Rubin; producers, Billy Higgins, Brams; co-producers, Ara Watson, Sam Blackwell; director, Colin Bucksey; writers, Watson, Blackwell, based on the book “Mother’s Day,” by Patricia MacDonald; camera, Bobby Stevens; editor, John A. Martinell; production design, Lindset Hermer-Bell; sound, Dan Daniels; music, Richard Hartley; casting, Shana Landsburg, Ross Clydesdale. Cast: Gregory Harrison, Roxanne Hart, Lacey Chabert, Timothy Busfield, Larissa Lapchinski, Maurice Godin , Victoria Snow, Patricia Hamilton, Jody Racicot, Arlene Mazerolle, Matthew Bennett, Kate Hennig, Patric Masurkevitch Slick, entertaining but with a muddled climax, “When Secrets Kill” probably made a more thrilling book (which it was) than a TV movie. Nonetheless, moppet thesp Lacey Charbet’s (“Party of Five”) lively perf, a tight script and snappy directing will keep auds tuned for the hollow denouement. Greg and Karen Newhall (Gregory Harrison and Roxanne Hart) are the adoptive parents of Jenny (Charbet) and are still trying to recover from Karen’s recent miscarriage. Teenage Jenny feels rejected because of her mother’s pain, and starts to act up and out. Meanwhile, Jenny’s biological mother Linda (Larissa Lapchinski) rudely pops up, unannounced, on Mother’s Day to meet the daughter she gave away. Jenny immediately gloms on to Linda, and recognizing a great way to torture Greg and Karen, calls Linda her “real mother” and turns up the brat meter to 11. Greg and Karen are furious at Linda’s self-centered intrusion, but they’re not the only ones, as Linda’s presence opens lots of old wounds and some well-kept secrets in the small town. Just as fast as she showed up to disrupt everyone’s lives, Linda is found dead, further disrupting the lives of the several townsfolk suspected of the killing. The last 40 minutes are spent in red-herring hell as Greg tries to track down the killer, with a lame payoff. Colin Bucksey keeps pace brisk and uses some interesting camera setup and optical effects to build wariness and tension, but Timothy Busfield, as police detective Walter Ference,is oddly somnambulistic, and it’s with his character that scripters Ara Watson and Sam Blackwell scrimped, giving the usually excellent Busfield a 2-D cutout. Ditto the handsome and likable Gregory Harrison and the lovely Roxanne Hart, but it’s young Charbet who really digs into her troubled pubescent role, and may prompt parents in the audience to yearn to give little Jenny a smack. Production design is lovely and rest of tech credits top-notch.