Rebecca mistakenly sends Josh a text meant for Paula and takes drastic measures to ensure he never sees it. Meanwhile, Paula and her husband attempt to rekindle their relationship, only to be thwarted by Rebecca.
Eve guest-stars as a rival glee club’s instructor. The Glee Club checks out their hair-raising competition, and Kurt gives Rachel a makeover.
In the past, young Zoro sparred constantly with a girl named Kuina, but he could never claim victory. They vowed that one of them would someday be the world's greatest swordsman – but tragedy intervened.
Leonard and Howard turn to Raj for help in dealing with a work emergency when they nearly come to blows after blaming each other for a potential disaster at the university. Amy throws an authentic Victorian Christmas party, while Sheldon seeks revenge on her for making him celebrate the holidays.
While Sheldon is in Texas, the rest of the gang realize how much he has changed their lives as they decorate the apartment for Christmas.
During a game, Sheldon revisits Christmas memories; Amy, Penny and Bernadette look for a date for Koothrappali.
When Leonard's former high school tormentor resurfaces, Leonard must confront him. Meanwhile, Penny realizes she did her fair share of tormenting in the past.
The guys find a "super" use for Penny's new boyfriend, Zack, when they enter a costume contest as the Justice League.
A Christmas visit from his mother has Leonard discovering she's kept a lot of news from him that she shares with Sheldon and worrying if she'll approve of his romance with Penny.
Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.