It's Trey's 21st birthday and Marissa, anxious to help Trey and Ryan forge a relationship, throws a birthday party for Trey at the Cooper-Nichol mansion that turns out to be a rager. Seth is left in hot water by both Summer and Zach, but why? Sandy wants to continue his friendship with Carter, leaving a confused Kirsten. Meanwhile, Julie shares some memories with an "old" friend and in the process learns a few things and gains a few ideas.

Sandy and the boys devise a plan to save Trey from going to jail after he took the fall for supplying drugs at his birthday party. Kirsten and Carter, fulfilling more than their editorial duties, take a trip to Featherbrook's winery. Meanwhile, Caleb returns home and questions his marriage with Julie.

Seth and Zach declare themselves rivals for Summer's affections; Marissa is still reeling from being nearly raped by Trey; Sandy confronts Kirsten when her drinking problem becomes very apparent; Caleb hands divorce papers to Julie.

Seth and Zach squabble over who should take Summer to the prom and who will meet George Lucas for dinner; Sandy takes drastic actions with a recovering Kirsten; Ryan starts to piece together what happened between Trey and Marissa, courtesy of Theresa; Julie's attempts to poison Caleb take a surprise turn.