It's Chrismukkah once again in The O.C. and this year, Seth wants to take it global. As Caleb is faced with the looming prospect of going to prison, Sandy convinces him to come forward and reveal the truth about his involvement with Renee. Julie and Jimmy spend some quality time together. Caleb's confession shocks the Cohen and Nichol family to the core, and nothing will be the same again.

After hearing about Lindsay and Ryan's failed attempt at dinner with Caleb the night before, Kirsten arranges a dinner that she can supervise. But her presence makes no difference when Ryan and Caleb butt heads and disaster strikes. Sandy keeps Rebecca's presence in Newport a secret from Kirsten after deciding to take her case to court. Marissa and Alex's relationship intensifies, while Seth and Summer spend a lot of time together at Zach's insistence.

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.

Social Chair Marissa tries to plan this year’s carnival but is having much difficulty due to a little pest named Taylor. Sandy is surprised to find Kirsten has been released from rehab but instead of informing him, she has been living with another woman named Charlotte who she met in rehab. Julie and Sandy meet with the Dean and Dr. Kim to discuss Ryan and Marissa’s future at Harbor High. Later Ryan and Marissa partake in a similar meeting. Elsewhere Jimmy meets a man and feels more than open to discuss his money problems with him.

Ryan decides to make a life-changing decision that Sandy reluctantly supports; Marissa looks to her new friends to help with her latest crisis with Ryan; Summer and Seth go on a mission to reveal a secret between Taylor and Dean Hess; Charlotte makes Julie an offer that she can't refuse.

Marissa visits Johnny at his house after his accident to see how he is doing. Julie and Kirsten get a contract for their new catering business while Sandy, Ryan and Matt meet with investors.

Ryan, Seth and Summer launch a campaign to get Marissa back into Harbour. With the help of Dr. Kim they get the board of trustees to hear the case will Marissa be permitted to return for her final semester?

Graduation is just weeks away and Ryan, Seth, Summer and Marissa leave Newport to attend their respective pre-frosh orientations at UC Berkeley and Brown. While dropping the boys off at the airport, Kirsten is surprised to see Theresa and her all-too-familiar-looking baby boy. While visiting Brown, Seth runs into Anna on the quad and they instantly connect. Could this be the end of Summer and Seth? Meanwhile, Kirsten and Sandy attend a hospital benefit where Kirsten vents her frustrations and falls back into an old habit.

Ryan and Volchok make a deal after a fallout at prom. Sandy is chosen as Man of the Year, but this sparks the DA to dig deeper into his involvement with the hospital problems. Marissa goes and sees Kaitlin at her boarding school and Seth visits the Newport Group HQ and lights up the joint.