Gossip Girl IV (5)

An anonymous Gossip Girl blast starts a very damaging rumor about one of Columbia's new students, Serena. On her path to greatness, Blair decides to take a class with a powerful businesswoman, Martha (guest star MARLYNE BARRETT -- Damages, Kings, The Wire), who is a guest lecturer at Columbia, but a mysterious fellow student thwarts her plans to secure the prized position as Martha's assistant.