Seth tags along with Ryan who travels to Enseniada, Mexico to look for the fugitive Volchok, and tries to hold off Ryan from doing something drastic. Back in Newport, there is a clothing drive at Harbor High, where Julie persuades Kaitlin to participate in it, until she learns Kaitlin's true agenda. At Brown University, Taylor pays Summer a surprise visit, but does not want to confide in her about her problems of her own back in France.
Volchok turns to Sandy for advice, without Ryan's knowledge. Summer prepares to face life in Newport as she returns from Brown. Meanwhile, Julie finds herself alone on Thanksgiving when she is not welcome in the Cohen's house.
Ryan can't sleep, and a smitten Taylor tries to seduce him by becoming his sleep therapist. Meanwhile, Seth vows not to call Summer, and Kaitlin struggles when Julie has a fling with her tennis instructor. Summer and Che take their activism to a new level, but pay the consequences later.
Summer gets kicked out Brown, thanks to her friend Che. Seth leaves Newport to visit Summer at Brown, but runs into Che. Ryan has fantasies about Taylor after kissing each other. And Kaitlin throws a party at Dr. Roberts house to get even with a popular girl. Meanwhile, Julie learns NewMatch is no longer just a dating service.
Kaitlin fails a class presentation and is forced to work with a smart classmate, whom she ends up liking. Seth and Summer move forward with their plans, regardless of how they really feel. Sandy confronts Frank on why he's in Newport.
Henri-Michel tells Ryan about Taylor's life in France, forcing him to question their relationship. Seth seeks Dr. Roberts' permission to marry Summer. Kaitlin realizes she likes Will. Summer reconnects with Holly and worries about her future. Meanwhile, Kirsten makes a shocking discovery at NewMatch.
Ryan tries to act like he doesn't miss Taylor, who is seeing a therapist. Kirsten's turning 40, but has her mind focused on other things. Julie is having an affair that Kaitlin does all she can to stop. Che makes a discovery about Seth.
Ryan and Taylor devise a plan to bring Julie and Frank closer, but Kaitlin tries to keep Bullit in Julie's personal life. Summer begins to have doubts in her relationship with Seth. Kirsten opens up about her past with Jimmy to Sandy as they prepare for their new baby.
Kaitlin does all she can to sabotage Julie and Frank's relationship. Ryan and Taylor tell each other how they feel. Summer encourages Seth to find something he's passionate about. Kirsten realizes what Newport's society is all about. As the night comes to a close, an earthquake hits Newport Beach.
After the earthquake, Ryan tells Seth he needs to get to the hospital, but doesn't want to worry Taylor. An aftershock leaves Kirsten wondering if her unborn baby is still alive. Taylor takes control when Summer and she hear an intruder in their home. Kaitlin and Julie are trapped in an ice cream store.
Six months after the trauma of the Newport earthquake, Ryan and the rest of the Cohens struggle with their living arrangements in the aftermath of the destruction of their house. Both Ryan and Taylor struggle with their feelings for each other despite knowing that they have nothing in common. Seth feels he's keeping Summer back from her activist work programs, but does not want to let go of her. Meanwhile, Julie, whom is now three months pregnant herself, is planning her upcoming wedding to Gordon Bullit, but Kaitlin realizes that she is not over Frank Atwood. Seth and Ryan visit the old house that Sandy and Kirsten lived in before there move to Newport Beach. When they pressure Sandy and Kirsten to visit their old house, where a gay couple now resides there, Kirsten happens to go into labor, and soon, Julie's wedding becomes Kirsten's baby birth scene.