TUESDAY, DECEMBER 30

"90210" � (8:00-9:00 p.m. ET)

"That Which We Destroy" (TV- PG) (HDTV)

JENNIE GARTH AND SHANNEN DOHERTY RETURN � Still in shock from the surprise arrival of their half-brother, Sean (guest star Josh Henderson, "Desperate Housewives"), Annie (Shenae Grimes) and Naomi (AnnaLynne McCord) put their arguing aside long enough to process the news. Harry (Rob Estes) and Debbie (Lori Loughlin) also deal with Sean's arrival by welcoming him into their home. Kelly (guest star Jennie Garth) offers Naomi and Annie advice about not letting Ethan (Dustin Milligan) get in the way of their friendship, while the gap between Brenda (guest star Shannen Doherty) Kelly widens. Naomi broadens her friendship base and begins hanging out with a new group of girls but is confronted by Annie in a lunch-room showdown. Silver (Jessica Stroup) is threatened by Christina (guest star Lauren London, "Entourage"), a cheerleader for the lacrosse team, when she shows too much interest in Dixon (Tristan Wilds). Meanwhile, Dixon is dealing with the arrival of Sean and how it will potentially affect his family. Jessica Walter, Michael Steger, Ryan Eggold and Jessica Lowndes also star. Melanie Mayron directed the episode with story by Allison Schroeder and teleplay by Caprice Crane (#111).