Bernadette makes Howard choose between herself and his mother, while Penny and Raj become upset when Priya returns to town and resumes her relationship with Leonard.
Sheldon invents a three-player chess game, Penny and Amy use Bernadette to spy on Leonard and Priya, and Raj tries a new drug to treat his social anxiety.
Howard believes that his mom suffered a heart attack because he told her that he's marrying Bernadette, Sheldon freaks out over germs, and Penny and Priya compare notes on Leonard.
Amy gets inadvertently caught in the middle of a fight between Sheldon and Penny over a chair. Leonard tries to add some spice to his long-distance relationship with Priya.
Penny sets up Raj with a deaf friend, not knowing that she's actually a gold digger, and Sheldon decides to let his minor decisions rest on the roll of the dice.
Sheldon takes offense when Leonard wants to attend a party with Wil Wheaton, while Bernadette tries to block Howard's opportunity to go into outer space.
Sheldon tries to get into the spirit of Halloween by trying to scare the guys after they prank him. Leonard seeks Penny's advice when an attractive comic book artist takes an interest in him.
When Stuart asks Amy on a date, Sheldon considers having a more serious relationship with her. Meanwhile, the guys become obsessed with a new card game involving Wild West heroes and witches.