For the annual Snowflake Ball, Blair (Leighton Meester) and Chuck (Ed Westwick) make a bet that they can find the ideal dates for each other. Aaron's (John Patrick Amedori) ex-girlfriend, Lexi (guest star Natalie Knepp), expresses an interest in Dan (Penn Badgley) which creates conflicted feelings for Serena (Blake Lively). Nate (Chace Crawford), Jenny (Taylor Momsen) and Vanessa (Jessica Szohr) get into a tangled situation that puts their friendships and hearts on the line.