Gossip Girl decides to liven things up at the Constance Billard and St. Jude's graduation by sending out a shocking and damaging email blast in the midst of the commencement ceremony, stirring Serena (Blake Lively) to come up with a plan of attack. The Mean Girls (guest stars Yin Chang, Nicole Fiscella, Amanda Setton and Dreama Walker) challenge Jenny (Taylor Momsen) to throw her hat in the ring to succeed Blair (Leighton Meester) as Queen Bee next year. Lily (Kelly Rutherford) and Rufus (Matthew Settle) struggle to repair their relationship after Lily’s betrayal. As for the cliffhangers, Blair and Chuck (Ed Westwick) finally…and Serena is shocked by…and Georgina (guest star Michelle Trachtenberg) decides to…and Dan (Penn Badgley), Nate (Chace Crawford) and Vanessa (Jessica Szohr) unknowingly….and it all happens in the series' climactic season finale.