Howard becomes depressed after Penny makes a cruel statement about his love life, while the rest of the guys prepare for a grudge killer robot duel against an obnoxious colleague at the university.
On a train to San Francisco, Howard, Raj and Leonard fight for the affections of sci-fi star Summer Glau, while Sheldon is forced to turn to Penny for help when he leaves his flash drive behind.
Leonard is upset when the owner of the comic book store goes on a date with Penny, so he convinces Howard and Raj to take him to a bar so that he can pick up a woman of his own.
After being dumped by Leslie, Howard heads to Las Vegas with Leonard and Raj. Meanwhile, Penny is forced to take in Sheldon after he locks himself out of his apartment.
Penny is forced to turn to Sheldon for help when she dislocates her shoulder in the bathtub. Meanwhile, the rest of the guys accidentally get stoned in the desert while waiting for a meteor shower.
Sheldon attempts to help Penny understand physics to impress Leonard, while Howard becomes jealous when Bernadette takes an interest in Leonard's research.