Two sneak previews of next Thursday's all-new episode of The Vampire Diaries reveal that the mysterious "Isobel," for whom the episode is named, is apparently in town.

But why - and what are the Salvatores, Alaric and Elena going to do about it?

In the first clip, Caroline tries to figure out why Bonnie and Elena are feuding. Then we cut to the classroom, where Damon receives some unexpected news from Alaric ...

[video url="http://www.tvfanatic.com/videos/isobel-sneak-preview-1/" title="Isobel Sneak Preview #1"] [/video]

Follow the jump to pick up the action in a second clip, where Damon tries to find out what Alaric knows, and Elena decides whether to meet Isobel for the first time.

Also below is a brief CW trailer for the episode, the penultimate installment of the terrific first season (the finale airs May 13). Take a look and comment away after:

[video url="http://www.tvfanatic.com/videos/isobel-sneak-preview-2/" title="Isobel Sneak Preview #2"] [/video]

[video url="http://www.tvfanatic.com/videos/vampire-diaries-trailer-countdown/" title="Vampire Diaries Trailer: Countdown"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.