When Ryan's brother, Trey, gets out of jail and gives Ryan a call, the Cohens give him a warm welcome. Though, Ryan knows nothing good can come from it. Zach returns from his Italy trip and gives some news leaving Summer curious and Seth ... not really sure what to think. Meanwhile, after Julie admits her naked mistake to Kirsten, they both agree to get Caleb in on it for more help. Newport Living is officially launched.

Sandy reluctantly serves as host/auctioneer at yet another OC benefit; Trey lies to Ryan to prove that he can be self-dependent; Carter reinvigorates Seth and Zach's comic book dream, much to the annoyance of Summer. Marissa moves in with the Cohens.

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.

Sandy, Seth and Ryan travel to Miami to visit the Nana after she tells Sandy she is getting married. Unable to go because of work, Kirsten is left on her own to deal with her feelings for Carter. Trey misinterprets Marissa's friendship; Zach invites Summer to a home-cooked dinner.

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.

Kirsten hits rock bottom after Caleb's funeral, prompting Sandy to finally take action; Jimmy Cooper resurfaces and almost immediately renews ties with a mourning Julie; Jess bullies Trey into participating in a drug deal that turns into a shootout; Ryan finally learns the truth about what happened between Trey and Marissa, leading to a bloody confrontation.

In the season three opener, we start off with senior year starting in a few days. It has been a couple of months since the shooting. Trey has been in a coma all this time leaving the D.A. impatiently waiting for his side of the story. Feeling the pressure from the community the D.A. continues to put pressure on Ryan, Marisa, Seth, Summer and others for more information. Meanwhile Julie is steaming mad because Caleb’s accountant won’t give up the goods on Caleb’s will and Kirsten is still in rehab.