Ryan, the Cohens, the Coopers and their friends build new lives, resolve lingering issues, face major decisions and undergo shocking personal transformations. No matter what happens or where they go, the members of this unique extended family all know that they will always have one another to turn to.
In the aftermath of a major earthquake that cuts off power and communication between the Cohens and their loved ones, Seth must take over Ryan's role as the protector when Ryan is injured and the boys are stranded on a deserted road. Elsewhere, Summer and Taylor worry about their missing boyfriends while searching for Summer's escaped pet rabbit - and the quake leads to an unexpected reunion for Taylor.
Newly engaged Seth and Summer both panic about the prospect of being married, but neither will break it off, despite the advice of their friends. Instead, they begin a complicated game of one-upmanship that almost leads them to Las Vegas for a wedding. Meanwhile, when Ryan's estranged biological father, Frank who has been in prison for years, tries to reconcile with Ryan, Sandy remains dubious.
As Valentine's Day approaches, Ryan worries that the pressure of the holiday will ruin his relationship with Taylor. Meanwhile, revelations from their pasts, along with a psychic's dire predictions, cause Summer and Seth to question whether or not they are destined to be together. Elsewhere, Kirsten reminisces about her own history and decides to share a long-held secret with Sandy, and Ryan begins to reconcile with his dad.
As the Cohens prepare for Kirsten's 40th birthday party, Kirsten gets some news that will change her life forever. Meanwhile, Julie is having a secret love affair and Kaitlin is doing everything she can to stop it. Elsewhere, while Ryan acts as if he doesn't miss Taylor, she visits a therapist who gives her some rules to live by, and Seth and Che's plan to save Newport's groundhog goes awry.