The O.C.

In the fourth season premiere, everyone struggles to adjust to life without Marissa.

Ryan travels to Mexico--with a stubborn Seth in tow--to put an end to his turmoil in the only way he knows how.

On Thanksgiving morning, the Cohens are still dealing with what happened in Mexico. Summer wonders if she can deal with Newport anymore.

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. Meanwhile, Kaitlin gets revenge on Julie. Taylor turns to Kaitlin for advice on Ryan.

When Seth visits Summer at Brown, he finds an empty dorm room.

It's time for another Chrismukkah in Orange County.

As the new year approaches, Ryan's romantic getaway for two is spoiled. Summer's future rests in the hands of a shady character.

Newly engaged Seth and Summer both panic about the prospect of being married, but neither will break it off.

Ryan questions his relationship with Taylor. Meanwhile, Seth visits Dr. Roberts in Seattle to ask for permission to marry Summer.

Che 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 an earthquake, Ryan is injured and the boys are stranded. Summer and Taylor search for an escaped pet rabbit.

In the emotional series finale of "The O.C.," Ryan, the Cohens, the Coopers and their friends build new lives, resolve lingering issues.