Marissa’nın ölümünden sonra Newport’ta hiçbir şey eskisi gibi olmayacaktır. Seth bir çizgi roman dükkanında çalışmaktadır. Ryan ise Marissa’nın ölümünü atlatmaya çalışmakta ve kendisini eski hayatına sürüklemeye çalışan güçlere karşı savaşmak zorundadır. Sandy ve Kirsten’in evliliğinde ise işler yoluna girmeye başlamıştır, ancak aileyi bir arada tutmak yine de kolay olmayacaktır. Bu arada Marissa’nın sorunlu küçük kız kardeşi Kaitlin’in de yardıma ihtiyacı vardır. Artık Brown Üniversitesi’nde okuyan Summer ise yeni arkadaşı Che ile beraber okulda eylemler düzenlemektedir.

Ryan ve Seth, Volchok’tan intikam almak için Meksika’ya gider. Bu arada Seth, Meksika’da aradığı şeyi bulmasına yardımcı olacak yeni arkadaşlar edinir. Sandy ve Kirsten ise onların peşinden gider. Harbor Lisesi’nin yeni disiplin komitesi başkanı ise Kaitlin ve Julie’yi aynı iş için beraber görevlendirir. Üniversiteli Summer ise hippi arkadaşlarıyla beraber bir ağacı kurtarmak için eylem yapmaktadır. Bu arada Taylor, Summer’a süpriz bir ziyarette bulunur.

Cohenlar’ın evinde Şükran Günü sabahı yaşanmaktadır ve aile hala Meksika’da olanları tartışmaktadır. Bu arada Volchok şehre dönmüştür ve Ryan intikam almak için sabırsızlanmaktadır. Sandy, önce Ryan’ı sakinleştirmeye çalışsa da sonunda Volchok’la yüzleşmesini sağlar. Julie’nin davranışları Kaitlin’i uzaklaştırır ve Dr. Roberts’la olan ilişkisini de tehlikeye atar. Bu arada tatilde ailesini ve Seth’i ziyaret etmeye hazırlanan Summer bunu yapıp yapamayacağını sorgulamaktadır. Öte yandan sevgili kızının Avrupa seyahati sırasında bir Fransız ile evlendiğini duyan Veronica, Taylor’ı evden kovar.

Seth, Summer’ı ziyaret ettiğinde üniversite hayatının onu değiştirdiğini ve o eski maddiyatçı ve dedikoducu Summer’ın yerinde yeller estiğini fark eder. Ryan, Taylor’a boşanma işlemleri konusunda yardımcı olmaya çalışacaktır. Öte yandan Julie ve Kaitlin de beladan kendilerini uzak tutmaya yemin eder, ancak bu o kadar da kolay olmayacaktır.

When Taylor learns about Ryan's sleeping problems she devises a plan to help him but must then turn to Kaitlin when her plan backfires. At Brown Summer and Che step up their activism and it lands them more freedom than imagined. Julie also gets help from Kaitlin to help save the dating service.

Kaitlin takes down the school mean girl by throwing a rager at her house. Sandy and Kirsten find time to bond with Ryan while Seth is away visiting Summer at Brown but all he finds is an empty dorm room. Meanwhile Julie continues work on the dating service and finds out a new surprise.

Chrismukkah once again returns to the Cohens. Ryan and Taylor have an accident while putting up the holiday lights and they end up in a sort of parallel universe, where all is not like it is meant to be, since Ryan does not exist. While - in the real world - everybody is worrying about them, except Taylor's mom, they eventually manage to fix things, also thanks to a letter from the past.

Ryan and Taylor may be heading out on a Las Vegas road trip for New Year's Eve, but there's even more fun in store when Seth and Summer join them. Meanwhile Julie doesn't trust NewMatch's new accountant, and Sandy suspects the reason why.

Kaitlin is assigned a tutor after she presented a ruffled report to her class. Julie comes clean to Kirsten about who Frank really is. Summer and Seth continue their recent commitment despite how they really feel about it. When Ryan's dad comes to the Cohen's for dinner things don't go as planned.

Taylor's ex-husband comes to Newport and causes a rift in her relationship with Ryan. Seth goes to Seattle to obtain Dr. Roberts blessing, while Summer "travels to the past" for 48 hours. Kaitlin finds love, while Julie finds problems with Kirsten.

Ryan overcomes his indecision and competes with Henri-Michel for Taylor's affections. Che leads Seth on a trek of spiritual renewal. Meanwhile, Kirsten and Julie have to do some damage control.

Sandy, Ryan and Seth prepare for Kirsten's upcoming 40th birthday party, however Kirsten learns some news that will change her life forever. Kaitlin tries to stop her mother having a secret love affair. Taylor visits a therapist and Ryan pretends that he doesnt miss her. Elsewhere Che finally learns that Seth isn't his soulmate.

Seth and Summer come upon a fortune teller whose prediction makes the two question whether they are truly meant for each other. Ryan gets back in touch with his father (with a little help from Taylor). When the two teens discover a love connection between Frank and Julie despite her pending engagement, a Valentine's competition is sparked between "Team Bullit" and "Team Frank". Meanwhile, with a new baby on the way, Kirsten finds herself dwelling on an old secret involving Jimmy Cooper.

In the immediate aftermath of a violent earthquake that rocks Newport, everyone struggles to stay together and keep their spirits up. Sandy and Kristen are stranded at the local shopping center where Kristen has an accident. Across town, Julie and Kaitlin are stranded in a demolished ice cream parlor on the pier with a pitiful worker of the place. Meanwhile, Ryan is seriously wounded with a piece of glass in his side, but keeps the news from Taylor to avoid panicking her. Seth soon learns of Ryan's condition and attempts to drive him to safety while Summer and Taylor search the ruins of the Roberts' house for Summer's missing rabbit, leading to Taylor having a confrontation with her mother.

The Cohen family says goodbye in the series finale as the episode jumps six months after the earthquake to show the Cohens, Ryan, Taylor, Summer and the Cooper women trying to piece their lives back together. The Cohens find out that fixing up their old mansion would cost more than rebuilding it but Ryan and Seth see this as an opportunity to give Sandy and an expecting Kirsten a surprise that'll change their lives.