When Ryan Atwood (Benjamin McKenzie), a tough, guarded, fiercely intelligent 16-year-old, plunges headlong into the wealthy, privileged community of Newport Beach, California, he soon discovers that the ruling families of Orange County are every bit as territorial as the tough crowd with which he ran on the streets of Chino. For Sandy Cohen (Peter Gallagher), the idealistic public defender who takes Ryan in; his wife, Kirsten (Kelly Rowan), the linchpin of OC society; their awkward adolescent son, Seth (Adam Brody); and the beautiful, troubled girl next door, Marissa Cooper (Mischa Barton)--Ryan's presence will forever change their lives.
At the end of the first season, the Cohen household had been reduced to two--parents Sandy and Kirsten, as the boys had flown the coop, moody Ryan back to Chino and goofy Seth for the wide expanse of the Pacific (somehow ending up in Portland, Oregon). Once the prodigal sons returned home, thanks to a lot of persuading, both tried to mend relationships with their former girlfriends, Marissa and Summer (Rachel Bilson). While friendships were solidified, everyone was dating someone else: Seth was with sultry club manager Alex (Olivia Wilde), Summer with sensitive polo jock Zach (Michael Cassidy), Ryan with smart girl Lindsay (Shannon Lucio), and Marissa with her family's pool guy and a bottle of vodka. Both Sandy and Kirsten found themselves tempted away by more-than-willing suitors, and wicked Julie (Melinda Clarke), Marissa's mom, cheated on new husband Caleb (Alan Dale) with ex-husband Jimmy (Tate Donovan). An extremely tangled web from which the show almost didn't recover.
In season three, Kirsten befriends a mysterious woman in rehab. Strapped for cash, Jimmy returns to Newport Beach and even tangles with Julie again--but he's in way over his head this time. After the shocking events at the end of her junior year of high school, Marissa finds herself in the role of a princess who has definitely been knocked off her pedestal, further straining her relationship with Ryan. With Marissa temporarily brought low, Summer's got some new competition for social chair. And although his marriage with Kirsten may be on the mend, Sandy may have to embark on a brand-new career as a result of the changes in Kirsten's life.
High school seems like a distant memory to the young graduates at the centre of The OC, particularly because they have been thrust into adulthood after the death of their beloved friend Marissa Cooper. The Cohens struggle to keep Ryan focused on the future, fighting the forces that threaten to pull him back into his old life. Having left Orange County, Summer attends Brown University in Rhode Island, where she has reinvented herself as a left-leaning, tree-hugging activist. And, lonely in Orange County, Seth works at a local comic book store. Much has changed for the residents of Orange County, but in the end, the bonds between them will never be broken.