It's Christmukkah and Kirsten asks Ryan if he wants to invite someone for dinner. Immediately Chino Kid remarks that he got that "someone" is clearly a subtle way for meaning Miss Townsend; anyway, in the end, Ryan tells Kirsten he'll ask to Taylor. Once alone in the kitchen, Ryan finds a letter for him. From Marissa Cooper. Meanwhile, Kaitlin and Julie are heading for Riverside, or better "the ghetto", as Kaitlin points out. They ask Taylor if she wants to go with them but she doesn't accept: she's sure Ryan will invite her to the Cohens. Unfortunately Ryan doesn't have the same idea. Taylor is hurt and follows Ryan upstairs, where they end up arguing and falling down the ladder. As soon as Ryan comes back to his pool house, he finds a stylish gym. In that moment Mrs. Cohen shows up. Kirsten IQ- Ice Queen - doesn't seem to know who he is and she warns him not to wander around her house. Then, Ryan sees that Julie is up to help Newport Beach's poor people. That's actually a shocker. Always more confused, Ryan drops by Seth's comic book shop and Seth is definitely as geek as he used to be when Sandy rescued Ryan from prison. Ryan can't believe that even Seth doesn't recognize who he is, and goes looking for Sandy, who, by the way, looks like Caleb 2 the revenge. Anyway, Sandy is the mayor of Newport, and he doesn't seem interested in listening to the kid. Yep, this is Newport Beach without Chino Kid. The next scene is set at the hospital. Ryan and Taylor are lying asleep. Summer, Seth and Sandy comes over and Kirsten informs them that the doctor said that's not a big deal but they've to wait until they wake up.
Taylor and Ryan meet and they end up admitting "We're in a parallel universe". Taylor is positive they're there in order to fix something happened in their past. Anyway, in that moment, they see Summer (dumb but fashion like she used to be when Ryan showed up in Newport Beach). Then, Che shows up and it turns out Summer and Che are about to marry. Taylor has a plan: to get Summer and Seth back together.
Back to the hospital, Taylor and Ryan have not woken up yet but Sandy comes up with an idea: to bring Christmukkah in there.
While Ryan is trying to catch up with Seth, he finds out Kirsten and Jimmy are married. At the same time, Taylor follows Che and it turns out Che and Julie are having an affair, even though Julie is married to Sandy. Actually Taylor finds out something else: Miss Cooper is coming back from Berkeley at three o'clock. As soon as Taylor informs Ryan about this, he tells her he wants to be let out of this. Taylor gets it: "Since Marissa is alive, you don't want to go back".
Back to the real world, Summer fills Kaitlin and Julie in on what's going on and they go looking for Taylor's mom. Kaitlin doesn't seem that sad that he whole Riverside trip is canceled. Meanwhile, at the hospital, Kirsten looks worried since she found Marissa's letter which Ryan found before.
It's three o'clock. Ryan looks for Marissa at the airport but she is not there. Another Cooper girl shows up, though. Kaitlin. Who let Ryan know Marissa died three years ago, during her trip to TJ.
Meanwhile, Kaitlin and Julie make it to reach Taylor's mom, who is about to catch a plane. Veronica doesn't seem eager to lose her plane but Julie remarks: "I will tell to security you have a bomb".
Christmas party. Taylor and Ryan make meet Summer and Seth and, then, Kirsten and Sandy. In the meantime, Taylor sees her mother. It turns out, in this parallel universe, Taylor is a boy. Anyway, as Taylor points out, something hasn't changed: "My mom is still a b!tch" and she stands up to her, claiming she can't treat neither her nor Taylor 2 like that.
Jimmy lets Sandy and Summer know he found Julie and Che making out. Awkward situation. Unfortunately Taylor comes back to the real world, leaving Ryan to deal with the whole thing. At this point, Ryan claims the couples that are meant to be (Summer and Seth, Kirsten and Sandy) and, in the end, he's kicked out of the party by Julie.
Julie and Veronica are finally at the hospital. As soon as Veronica sees Taylor walking, she's not that enthusiastic she missed the plane. Taylor assures her she can catch the last plane, and Veronica leaves without turning her back. Kirsten and Julie have sympathetic faces but Taylor claims she's fine. Then, Kirsten gives something to Julie. The letter. Marissa wrote it to Ryan when she was about to leave after graduation day. "She had to leave Newport. It was the only way they could get on with their life. She loved him but she had to say goodbye".
Ryan ended up in prison but Sandy bails him out. He is positive what Ryan did say actually made sense. Sandy asks him he wanted to come over for dinner but he doesn't accept. Actually he heads for the pier, where he and Marissa used to meet up, before or after their DI - drama issues. Ryan sits there and read Marissa's letter and "Into dust" - by Ashtar Command - is playing in the background. Then he walks away.
In the real world, it stops raining and Ryan wakes up. It's finally time to celebrate Christmukkah.