THURSDAY, OCTOBER 6

"THE VAMPIRE DIARIES" - (8:00-9:00 p.m. ET)

"Disturbing Behavior" (Content Rating TBD) (HDTV)

FAMILY TIES - Still in Chicago, Klaus (Joseph Morgan) uses Gloria (guest star Charmin Lee), a witch he knew long ago, to help him track down missing information that will explain why his plan isn't working. Gloria's spells reveal intriguing glimpses of the truth, but she soon realizes she needs Stefan's (Paul Wesley) knowledge to complete the puzzle. When Stefan suddenly finds himself in danger, help comes from a surprising ally. Back in Mystic Falls, a frustrating new enemy pushes Damon (Ian Somerhalder) over the brink and he lashes out in a way that will have lasting consequences. Caroline (Candice Accola) struggles with her own emotional issues, even as she tries to help Elena (Nina Dobrev) face her feelings. Jeremy (Steven R. McQueen) makes a brief but disturbing breakthrough with one of his ghostly visitors, leaving him more confused than ever. Finally, Bonnie (Kat Graham) has a strange encounter that will affect everyone. Matt Davis also stars. Wendey Stanzler directed the episode written by Brian Young (#304).