The O.C.

Seth spent the summer teaching sailing and living in Portland, Oregon, but Seth’s parents have been unable to convince him to return home. Both Summer and Marissa try to forget their ex-boyfriends. Caleb becomes increasingly paranoid about his business. Meanwhile, Ryan lives a suffocating domestic existence with his pregnant girlfriend, Theresa, in Chino, working on a construction site.

Summer is over, and school is in session. Seth and Ryan hope to win back the attention they once had from Summer and Marissa. Hailey tells Jimmy about her plans to move to pursue unfulfilled fashion ambitions. To keep her near, Jimmy does something unimaginable. Meanwhile, Sandy explains to Julie that the district attorney is keeping a close watch on Caleb.

At the Bait Shop, the new music club, Seth gets help from his attractive and tough-talking manager, Alex, to prove that his friends don't know him as well as they think. Meanwhile, Summer gives some thought to how she really feels about Seth. Marissa is happy to share an evening with Ryan. But at school, Ryan has a confrontation with new classmate Lindsay.

Seth, now without a girlfriend, and Sandy, who has just been fired from the law firm, embark on new eras in their lives and vow to take the whole family with them. Ryan and Seth go on an awkward double date to see THE KILLERS perform at the Bait Shop. Meanwhile, Julie finds herself overwhelmed by her new role at the Newport Group and, as usual, is forced to turn to Kirsten for help.

The winter season finally comes to Newport, and Seth, Ryan, Summer and Marissa attend the annual SnO.C. Winter Ball. Julie and Jimmy spend some quality time together as the chairs of the host committee, and Sandy gets closer to the truth Caleb has been hiding. Meanwhile, Julie discovers Marissa's secret when Marissa leaves school at lunch and goes home to meet D.J.

The whole gang is invited to Chrismukkah at the Cohens' house, but Seth's favorite holiday is nearly ruined as secrets are revealed that will change the Cohen family forever. Summer, Marissa and Ryan make a plan to save Chrismukkah. Chrismukkah episode

Ryan tries to come to terms with his feelings for Lindsay now that she may become a member of the Cohen family. Meanwhile, Caleb learns that the criminal charges against him have been dismissed. Seth tries to cultivate a "bad boy" image. Marissa sees Jimmy and Julie kissing aboard his boat and is hurt and angry. Jimmy realizes that the best thing he can do is to leave Newport and move to Maui.

Lindsay and Ryan grapple with their new relationship: Is Lindsay Ryan's step-aunt or his girlfriend? Meanwhile, Summer meets Zach's family, and it doesn't go so well. In the end it's an anniversary to remember as Sandy surprises Kirsten with a serenade at the Bait Shop. But Marissa ends up alone as D.J. leaves Newport Beach.

It's girls against boys when Marissa and Summer plan a girls' night out and include Lindsay in the festivities. Ryan, Seth and Zach, have a bonding session over video games and pizza but find it hard to stay away from their female counterparts. Julie and Kirsten collaborate on an idea to help the image of the Newport Group while Sandy and Caleb try to convince them there may be a better way.

Seth and Zach decide to create a comic book based on their lives in Newport Beach. Summer wonders why she's been left out. Sandy decides to help an old friend, Professor Max Bloom, find his daughter, Rebecca, but the search leads to even more questions. While Julie is away, Marissa's contempt for Caleb grows. Meanwhile, Ryan tries to help Lindsay satisfy her curiosity about Caleb.

Summer decides to take an active role in creating the comic book, but Seth doesn't know if he can handle spending that much time alone with her. Sandy and Rebecca reminisce as Kirsten tries to convince Caleb he could have a familial relationship with Lindsay. Meanwhile, Caleb decides what kind of future he wants to have with his daughters. And Alex asks Marissa where their friendship is going.

Sandy tries to make amends with Kirsten for keeping Rebecca's return a secret by showering his wife with Valentine's Day gifts. Zach, Summer and Seth drive to San Diego to pitch their comic book idea. Julie returns from her European vacation and has decided to reconnect with Marissa. Meanwhile, Ryan wants to spend Valentine's Day with Lindsay, but her loyalty to Caleb gets in the way.

While Rebecca (recurring guest star KIM DELANEY) pays her last respects to her father, Kirsten grows impatient with Sandy's long absences from home and decides to visit Rebecca. Alex (recurring guest star OLIVIA WILDE) invites Marissa to hang out with her friends. Meanwhile, Caleb decides to remove all doubt that Lindsay (recurring guest star SHANNON LUCIO) is his daughter.

It's raining in Newport. Marissa tells Julie that she and Alex are dating and decides she has to get out of Caleb's house. Summer is faced with a big decision as she prepares to go to Italy with Zach. Ryan convinces Lindsay to take the paternity test, and everyone anxiously awaits the results. Meanwhile, Sandy is stranded in a motel room with nothing but a few snacks, champagne and Rebecca.

Although she is trying hard to make her new living situation work, Marissa feels she needs a break and agrees to join Summer, Seth and Ryan at the mall. Julie and Kirsten await the arrival of Carter, the new editor of Newport Living, but Julie is distracted when she's visited by Lance, an opportunistic man from her past. Meanwhile, Sandy and Caleb finally bond over all of their recent experiences.

Seth is determined to bring back the spirit and fun times of last year and won't stop until his plan is successful. Alex's jealousy is fueled when Marissa enlists an unlikely partner to help her with the school bonfire. Meanwhile, Kirsten wants Carter to continue with the magazine despite his reservations, and Sandy helps Julie keep her blackmailer at bay.

When someone from Ryan's past comes for a visit, he worries that nothing good can come of it; while the Cohen family welcomes the Chino visitor with open arms. As Marissa and Ryan continue to explore their newfound friendship, Seth and Summer face some unforeseen news. Meanwhile, Julie admits her mistake to Kirsten and looks to Caleb for help.

When Sandy becomes the honorary chairman of the Newport Beach charity yard sale, he solicits help from Trey. While Sandy auctions off Newport's finest, Kirsten and Carter share a table. When one of the auction's most expensive pieces goes missing, Ryan and Seth could also use some help. Meanwhile, Trey looks for a more permanent place to live as the Cohens welcome yet another houseguest.

Marissa hosts a birthday party for Trey at Caleb's mansion that quickly gets out of control. After surfing with Carter, Sandy suggests introducing him to a woman friend. When Summer finds out what Seth's potential graphic novel publisher, Reed, is really like, Seth is in big trouble. And after leaving town in disgrace, Julie returns and surprisingly ends up reminiscing with an old acquaintance.

After the wild party at Caleb's mansion, Sandy, Seth and Ryan devise a plan to save another Atwood from going to jail. Kirsten and Carter (recurring guest star BILLY CAMPBELL), fulfilling more than their editorial duties, take a trip to the wine country. Meanwhile, Caleb returns from Europe and rebuffs Julie's romantic advances. The band DEATH CAB FOR CUTIE performs.

Sandy, Seth and Ryan travel to Florida to visit Seth's Nana, Sophie, in Miami Beach. While playing shuffleboard, Seth and Ryan meet Mary-Sue, who helps Seth get center stage on the Music Video Nation spring break television special, hosted by Swerve, along with Pixie, a star of "Sherman Oaks: The Real Valley." Meanwhile, Carter leaves Kirsten alone at the offices of Newport Living.

Since Carter's departure, Kirsten has been drinking more than just tomato juice for breakfast. Marissa's nervousness around Ryan leads him to wonder if something has happened between her and Trey. Summer, tired of Seth and Zach behaving foolishly, confronts Reed about the graphic novel. Meanwhile, Caleb shows Julie that a picture is worth a thousand words.

Sandy and Caleb confront Kirsten about her behavior. Ryan heads home to Chino, as he looks for the truth about Trey and Marissa. Meanwhile, Summer refuses to let her three-way relationship with Zach and Seth stop her from attending the prom. And, Julie and Caleb toast to their final evening together as husband and wife.

Familiar faces show up for a final farewell to Caleb. Meanwhile, Sandy takes action to help Kirsten. And when Ryan learns about the Trey-Marissa incident, a showdown - if not a tragedy - is inevitable.