It's Trey's 21st birthday and Marissa, anxious to help Trey and Ryan forge a relationship, throws a birthday party for Trey at Caleb's mansion that quickly gets out of control. Sandy and Carter hit the waves together and decide to double-date and Summer discovers Reed's true identity, leaving Seth in hot water. Meanwhile, Julie leaves town on the heels of her disgrace, but comes home and reminisces about the Whitesnake concert with an "old" friend.