What's Carter Baizen (guest star Sebastian Stan, who dates Leighton Meester in real life) doing back on the Upper East Side, and how does his return coincide with Chuck's search for mystery girl Elle? Check out the clip below for a Gossip Girl teaser ...

[video url="http://www.gossipgirlinsider.com/videos/the-age-of-dissonance-sneak-preview-3/" title="The Age of Dissonance Sneak Preview #3"][/video]

Meanwhile, Vanessa is helping Serena act cool and knowledgeable about literature to impress a new guy. Follow the link for two more previews from "The Age of Dissonance" ...

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