The O.C.

In the fourth season premiere, everyone struggles to adjust to life without Marissa. Dealing with her death in the only way he knows how, Ryan has moved out of the Cohen house. When Ryan misses a special dinner, Seth finds him in the wrong part of town and calls Summer for help. Meanwhile, Julie Cooper (series star MELINDA CLARKE) will do anything--even yard work--to avoid dealing with the loss of Marissa. Kaitlin earns a new pair of boots from Dr. Roberts in true Cooper fashion. And Taylor Townsend (series star AUTUMN REESER) hides out in the diner and tries to convince her friends that she is in Paris.

Ryan travels to Mexico--with a stubborn Seth in tow--to put an end to his turmoil in the only way he knows how, but he comes up empty in quest for revenge. Meanwhile, Seth meets some new friends in Mexico, including a Marine (STEVE-O - "Jackass"), who help him find what he is looking for. Harbor School's new female dean of discipline, Dean Torres (TIA CARRERE - "True Lies," "Relic Hunter"), forces Kaitlin and Julie to work together on Harbor's clothing drive. And the Cohens ostracize Julie when they discover that she was part of Ryan and Seth's activities. Also, after Taylor visits Summer unannounced, the truth about Paris comes out, and Summer continues separating herself from everything related to OrangeCounty.

It's Thanksgiving morning at the Cohen house, and the family is still dealing with what happened in Mexico. Sandy makes a deal to help Volchok (recurring guest star CAM GIGANDET) but lets Ryan intervene and finally settle the score. Meanwhile, as Summer packs for a trip home to visit her family and Seth for the holiday, she wonders if she can deal with Newport anymore. And unable to cope with either Kaitlin or Dr. Roberts (recurring guest star MICHAEL NOURI), Julie spends most of Thanksgiving alone.

When Summer tries to become the gossip-loving girl she once was, she realizes that Brown may have changed her forever. Fortunately, Seth continues to be supportive of the new Summer through all of her endeavors. Similarly, Ryan empathizes with Taylor and surprisingly helps her out of a bind. Meanwhile, Julie and Kaitlin attempt to stay out of trouble, but neither can resist temptation.

Summer and Che (recurring guest star CHRIS PRATT) take their activism to a new level, resulting in more freedom than they expected. Meanwhile, after Julie flirts with a hot tennis instructor whom Kaitlin likes, the younger Cooper gets her revenge at a charity party. But later, Kaitlin helps save Julie and Kirsten's dating service. Attracted to Ryan, Taylor tries to cure his insomnia with her own therapeutic plan. When all of her schemes fail, she turns to Kaitlin for advice on how to get her way with Ryan.

When Seth visits Summer at Brown, he finds an empty dorm room. Meanwhile, Sandy and Kirsten take advantage of an opportunity to bond with Ryan, who is in a Taylor-induced haze. Kaitlin meets the mean girl of Harbor School and tries to best her by throwing a huge party at the Roberts house. Julie learns that Newmatch is more than just a dating service. And the truth about Che (recurring guest star CHRIS PRATT) comes out.

It's time for another Chrismukkah in Orange County. After Ryan and Taylor have an accident while hanging holiday lights, they realize that everything is not as it seems, and they must do whatever it takes to make things right again. Former series star TATE DONOVAN guest stars as Jimmy Cooper.

As the new year approaches, Ryan plans a special surprise road trip for Taylor and himself. But when Summer confronts Seth about not making any plans, Ryan's romantic getaway for two is spoiled. Later, Summer's future rests in the hands of a shady character that the gang meets on the way to Las Vegas. Meanwhile, Julie's accounting practices come under some unwanted scrutiny.

Newly engaged Seth and Summer both panic about the prospect of being married, but neither will break it off, despite the advice of their friends. Instead, they begin a complicated game of one-upmanship that almost leads them to Las Vegas for a wedding. Meanwhile, when Ryan's estranged biological father, Frank (recurring guest star KEVIN SORBO), who has been in prison for years, tries to reconcile with Ryan, Sandy remains dubious--and his instincts about Frank may just be correct. Also, rebellious Kaitlin's teacher orders her to be tutored by an insightful classmate, Will Tutt (recurring guest star musician CHRIS BROWN).

Taylor's ex-husband, Henri-Michel (HENRI LUBATTI), gets a little too close to home while promoting his erotic memoirs. After Henri-Michel tells Ryan about Taylor's exciting life in France, Ryan questions his own relationship with Taylor. Meanwhile, Seth visits Dr. Roberts (recurring guest star MICHAEL NOURI) in Seattle to ask for permission to marry Summer, who gets a vision of her future. And Kaitlin realizes that she likes Will (recurring guest star CHRIS BROWN), but she is concerned he thinks she's too shallow.

Che (recurring guest star CHRIS PRATT) and Seth take a trip to a forest, where Che has a dream and discovers that his spirit might be in love with someone unexpected. Afterwards, Seth and Summer finally speak for the first time since she rejected his marriage proposal. Meanwhile, Taylor decides that she can no longer associate with Ryan. Julie works her way back into Kirsten's life in the only way she knows how. And Kaitlin shuts out Will (recurring guest star CHRIS BROWN).

As the Cohens prepare for Kirsten's 40th birthday party, Kirsten gets some news that will change her life forever. Meanwhile, Julie is having a secret love affair--and Kaitlin is doing everything she can to stop it. While Ryan acts as if he doesn't miss Taylor, she visits a therapist who gives her some rules to live by. After Seth and Che's (recurring guest star CHRIS PRATT) plan to save Newport's groundhog goes awry, Che finally realizes that Seth is not his soul mate. And Sandy and Kirsten have surprises in store for each other.

As Valentine's Day approaches, Ryan worries that the pressure of the holiday will ruin his relationship with Taylor. Meanwhile, revelations from their pasts--along with a psychic's dire predictions--cause Summer and Seth to question whether or not they are destined to be together. Kirsten reminisces about her own history and decides to share a long-held secret with Sandy. Ryan begins to tentatively reconcile with his father, Frank (recurring guest star KEVIN SORBO), thanks to Taylor's meddling. And Julie must choose between Frank and the man whom Kaitlin wants her to marry.

Taylor eagerly prepares for her first real birthday celebration, but she frets over the fact that Ryan has still not told her he loves her. Even more concerning is the fact that she has secretly applied to and been accepted at Berkeley, the same school Ryan is going to attend. Summer helps Taylor come up with a plan to help Ryan express his feelings. Meanwhile, Kaitlin misbehaves outrageously in reaction to Julie dating Frank (recurring guest star KEVIN SORBO)--but Julie finds out there's more than just the usual Cooper rebelliousness behind Kaitlin's actions. Kirsten deals with more than her share of catty Newport women when she joins a yoga class. Summer wishes Seth were passionately interested in something, the way she is about the environment. And a powerful earthquake shakes Newport Beach.

In the aftermath of a major earthquake that cuts off power and communication between the Cohens and their loved ones, Seth must take over Ryan's role as the protector when Ryan is injured and the boys are stranded on a deserted road. Summer and Taylor worry about their missing boyfriends while searching for Summer's escaped pet rabbit--and the quake leads to an unexpected reunion for Taylor. Trapped in a ruined ice cream shop, the scared Julie and Kaitlin spend the time bonding and dealing with an amorous clerk--until they are saved by the only man in Newport for Julie. And Sandy takes charge of the frightened crowd in a damaged shopping mall.

In the emotional series finale of "The O.C.," Ryan, the Cohens, the Coopers and their friends build new lives, resolve lingering issues, face major decisions and undergo shocking personal transformations. No matter what happens or where they go, the members of this unique extended family all know that they will always have one another to turn to.