The O.C.

A troubled teen boy's life is forever changed when, upon landing in jail for a crime his brother committed, a public defender from Orange County, California decides to take him into his home.

Ryan decides to run away from Newport before he can be put into foster care. Seth and Marissa help him find a place to stay without being found.

Ryan's mother arrives in Newport.

It's the annual Cotillon Ball. Ryan continues to pursue Marissa, Seth makes friends with a newcomer, and Jimmy finds himself in hot water.

Ryan takes a job at the Crab Shack diner where a co-worker, named Donnie, might mean bad news for the Newport kids when he takes Ryan and Seth out to party queen Holly Fischer's parties where drugs and alcohol flow freely. Ryan asks Marissa out on a date, and when Luke again tries to intervene, Donnie decides to take matters in his own hands when he tries to starve off Luke... with a gun. Meanwhile, Sandy attempts to help Jimmy sort out his life, and gives him some bad news that be may go to jail for his unauthorized loans to cover his tracks. Also, Julie reveals a ...

On his birthday, Kirsten's father pays a visit to Newport with his 24-year-old girlfriend, but things get messy when the girlfriend makes advances towards Ryan.

Ryan, Seth, Marissa, and Summer plan a trip to Tijuana. The trip descends into chaos when secrets are revealed and lives are put on the line.

It can't stay in Mexico. Not after heartbroken Marissa took all those pills. And not with Marissa's mom trying to have her institutionalized - something Ryan, Seth, Summer and Marissa don't want to happen.

Calculus. AP English. History. The ways of the human heart. Not everything learned at Harbor High is on the schedule of classes. The Cohen casa is a house divided when Sandy takes an environmental case against Kirsten's father.

Work keeps Sandy and Kirsten apart, Rachel makes a play for Sandy, Julie's secret lover is revealed and - omigod! - Summer realizes she likes Seth (but don't ever tell anyone).

Thanksgiving dinner at the Cohens descends into bedlam when unexpected guests arrive. Ryan returns to his hometown when his brother calls on him for a favor.

No one was supposed to see what happened. But Luke did. And so did Ryan. Now, somehow, all Newport knows that Luke's dad has been living a lie. And subsequent gossip raises questions of secrecy and trust.

Ryan is introduced to a Cohen family tradition as unpleasant memories of the holidays back home resurface. Marissa sinks deeper into depression.

It's New Year's Eve. Ryan may have competition for Marissa's affections. Kirsten's sister stirs up trouble.

Ryan doesn't know much about Oliver, Marissa's therapy friend, but he knows he doesn't like him. Yet, Ryan still assists Oliver when he runs into trouble with the law at a Rooney concert.

He says he's a friend. But who can believe a word Oliver says? During a group getaway in Palm Springs, Ryan is sure he's wise to Oliver's game. Marissa is just as sure Oliver is a friend who needs help.

People who won't be on each other's Christmas-card list: Ryan and Oliver. Their rivalry for Marissa intensifies, with Ryan risking his standing at Harbor to unmask Oliver's true character.

Now sure of the truth, Ryan races against time to keep Oliver from hurting himself or Marissa.

On Valentine's Day, everyone is preparing for the Valentine's singles benefit dance. Luke has a new crush: that being Marissa's mother Julie. Meanwhile, Sandy gives Seth some sex advice over his dating of Summer. Theresa Diaz, an old friend Ryan's, shows up in town as part of the catering services for the benefit, which forces Marissa to lay her feelings on the table that her breakup with Ryan may have been a mistake. Also, Seth and Summer take their friendship to another level.

The Ryan-Marissa thing is more iffy than ever when Theresa hangs in Newport. The telenovela-like suds-o-rama overflows with the Seth-Summer follies, the Luke-Julie fling and an insider who may be a threat to the Caleb-Kirsten biz.

Anna is leaving. Theresa is staying. Seth thinks he's the reason for Anna's planned return to Pittsburgh. And Ryan knows he's why Theresa is staying. But what is either guy going to do about it? Caleb is Riviera's Man of the Year (uh-oh).

Operation Protect Marissa! Seth and Ryan plan to keep Marissa from finding out about her mom's affair. It also becomes Operation Rescue Hailey when they inadvertently attend a Hollywood party where she's a stripper.

Marissa runs away after learning a heartbreaking truth, to a place where only Ryan could find her. Sandy's mother visits for Passover.

Engagement announcements are joyful news, right? Not when it means the one person Kirsten despises will become her stepmom. And not when Marissa will have a new family arrangement she doesn't want.

Julie's wedding shower is anything but uneventful. Seth has lunch with Summer's dad.

The Cohen men, along with Ryan and Caleb set out to Las Vegas for a bachelor party. Meanwhile, the girls are having fun with their own adventures.

On Julie and Caleb's big day, Ryan may be leaving Newport forever. Everyone handles it differently.