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.

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.

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 but lets Ryan intervene and settle the score.

When Summer tries to become the gossip-loving girl she once was, she realizes that Brown may have changed her forever.

Summer and Che take their activism to a new level, resulting in more freedom than they expected. Meanwhile, Julie flirts with a hot tennis instructor whom Kaitlin likes.

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.

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.

As the new year approaches, Ryan plans a special surprise road trip for Taylor and himself. Summer confronts Seth about not making any plans.

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.

Taylor's ex-husband, Henri-Michel, gets a little too close to home while promoting his erotic memoirs. Henri-Michel tells Ryan about Taylor's exciting life in France.

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.

As the Cohens prepare for Kirsten's 40th birthday party, Kirsten gets some news that will change her life forever.

As Valentine's Day approaches, Ryan worries that the pressure of the holiday will ruin his relationship with Taylor.

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.

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.

In the series finale of "The O.C.," Ryan, the Cohens and the Coopers build new lives, resolve lingering issues, face major decisions and undergo shocking personal transformations.