Plot summary
In a flashback to the 1980s, 17-year-old Lily Rhodes gets kicked out of boarding school and runs away to Los Angeles, reconnecting with her estranged older sister, Carol. Back in the present day, Blair and Nate attend their senior prom together, but the evening does not turn out exactly as planned due to Chuck's tricks. Serena and Lily do not see eye-to-eye over Serena's recent run-in with the law. Title reference: The 1983 film Valley Girl. Special guest star No Doubt performs in the flashbacks as a 1980s band called Snowed Out.
Credits
Adapted from Wikipedia contributors, Gossip Girl season 2. HTML formatting and reference markers removed.