Synopsis: Sandy and Jimmy buy a restaurant; Julie irks Kirsten by becoming the new model-home designer at the Newport Group; Seth is jealous of Summer's new boyfriend; Ryan is out to expose Oliver.

Synopsis: Abandoned by the gang for attacking Oliver, Ryan makes an unlikely ally to help him dig up the truth about Mr. Trask, whose increasingly scary behavior leads to a life-or-death crisis for Marissa. Meanwhile, Julie finds a surprising source of comfort after Caleb dumps her; and Anna reaches her boiling point over the chemistry between Seth and Summer.

Synopsis: Marissa tries to mend her relationship with Ryan, but he can't forgive her for the situation with Oliver. Things become even more complicated when Theresa, Ryan's ex from Chino, arrives to cater the Valentine's Day dance. Meanwhile, Seth and Summer decide to take their friendship to a new level, and Jimmy finds out he has a secret admirer in the Cohen house. 

Synopsis: Ryan and Marissa begin their life together as "friends", but both discoverthat it might be harder to do than to say. Theresa drops into Newport for work, and another visit. Julie and Luke discover the meaning of "booty calls", and Seth and Summer make a declaration. 

Synopsis: Anna announces that she is leaving Newport to go back to Pittsburgh, which leaves Seth feeling saddened and guilt-ridden. Legal troubles brew for Caleb and Kirsten while Sandy works to solve them. Luke and Julie's secret romance is getting harder to contain, and Theresa brings a bit of trouble from Chino to the O.C. 

Synopsis: When actor Grady Bridges invites Summer and Marissa to his birthday party they head to L.A. with Ryan and Seth. Meanwhile in Orange County Jimmy and Sandy present their restaurant to Newport's finest and approach Caleb for some financial help.

Synopsis: The Cohen family prepares for a visit from Sandy’s mother. She’s comingfor Passover dinner, but Seth wants to make sure she doesn’t meet Summer during the festivities. He thinks his “Nana” won’t approve of her, but Summer is out to prove him wrong. Meanwhile, Ryan desperately looks for Marissa, who disappeared when she found out about Luke and Julie’s affair. 

Synopsis: Luke is desperate to explain himself to Marissa, but she isn’t ready to speak to him or her mother. But when Luke gets into a near-fatal accident,Marissa and Ryan decide it’s time to hear what he has to say. Meanwhile, it’s opening night for The Lighthouse. Just prior to opening, Jimmy and Sandy are shocked to find out the liquor license has been denied... Caleb surprises everyone when he proposes to Julie... 

Synopsis: It's Julie's wedding shower and Marissa will make it a day to remember! Meanwhile Ryan's world is turned upside down when Theresa returns with some shocking news and Seth is meeting Summer's daddy!

Synopsis: The boys head to Vegas for Caleb's bachelor party. But does Caleb have more than drinking and strippers planned? And will Sandy and Jimmy let that stand? In the meantime in Orange Country, a reluctant Kirsten has to plan Julie's bachelorette party.

Synopsis: It's Julie and Caleb's wedding day and it's going to be a day to remember for more than the blushing bride since this is only the tip of the iceberg as everyone's lives are forever changed!