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.

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.

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.