Gossip Girl decides to send a shocking email blast in the graduation ceremony of Constance Billard and St. Jude’s, pushing Serena to device a devious plan of attack. The Mean Girls Club challenge Jenny to succeed Blair as Queen Bee for next year. Lily and Rufus struggle with their relationship after Lily’s betrayal. As for the cliffhangers, Blair and Chuck finally…and Serena is shocked by…and Georgina decides to…and Dan, Nate and Vanessa unknowingly…

In a flashback to the 80s, 17-year-old Lily Rhodes (Brittany Snow) gets kicked out of boarding school and runs away to Los Angeles, reconnecting with her parents, Rick (Andrew McCarthy) and Cece (Cynthia Watros), and sister, Carol (Krysten Ritter). Back in present day, Blair and Nate attend prom together, but the evening doesn’t turn out exactly as planned and Chuck and Serena have a little something to do with that. Serena and Lily don’t see eye-to-eye over Serena’s recent run-in with the law. No Doubt performs in the flashbacks as an 80s band called “Snowed Out.”

Blair puts pressure on Georgina to making amends for her past bad behavior by helping her in an evil plan. The rivalry between Nate and Chuck over Blair reaches a boiling point. Lily makes a secret plan to help Rufus with Dan’s college tuition.