Sheldon feels lost after one of his favorite TV shows gets canceled too soon, so Amy tries to help him get over his compulsive need for closure. Meanwhile, Raj discovers a secret about his new love interest, Lucy.
When Howard finds a letter from his father, he's forced to confront his past, struggling with whether or not he should open it. And Leonard and Penny throw a "grown-up" cocktail party at the apartment.
Back to school! Leonard, Sheldon and Howard try to advance the cause of women in science by speaking with junior high girls about their future careers, while Raj plans his date with Lucy (guest star KATE MICUCCI).
After a terrible date, Raj vows to never leave his apartment again. Meanwhile, Penny actually impresses Sheldon with her acting skills.
While the guys try to give their significant others the perfect Valentine's Day, Raj and Stuart throw a lonely people party at the comic book store.
A fight between Leonard and Sheldon drives Leonard to finally move in with Penny - not realizing how the shift will affect Penny and Amy's living arrangements. Meanwhile, Raj takes care of Mrs. Wolowitz while Howard is away.
Outraged that he's being forced to work with his university nemesis, Barry Kripke (guest star JOHN ROSS BOWIE), Sheldon faces a crisis of conscience. Meanwhile, Howard and Raj spend a thousand dollars on action figures of themselves.
While the guys take a road trip to a comic book convention in Bakersfield dressed as characters from Star Trek: The Next Generation, Leonard's car is stolen. Meanwhile, the girls stay home and try to appreciate the world of comics.
Sheldon is accused of sexual harassment at the Univesity and winds up dragging Leonard, Raj and Howard into the fray. Southland's REGINA KING guest stars as the University's Director of Employee Relations.
Sheldon unwillingly revisits some Christmas memories during a lively game of Dungeons and Dragons, while Penny, Bernadette and Amy try to find the perfect girl for Raj when he joins the girls for ladies night.
Sheldon plays nursemaid to a sick Amy, while Howard attempts to bond with his father-in-law (guest star CASEY SANDER) on an upcomingfishing trip.
When the University reassigns Sheldon's (unused) parking spot to Howard, the ensuing turf battle affects the whole gang.
Howard and Raj try to get to the bottom of why Sheldon disappears every afternoon at 2:45. Meanwhile, Leonard and Penny wrestle with jealousy in their relationship.
Bernadette pressures Howard to move out of his mother's house, while Sheldon finds himself caught in the middle of a fight betweenAmy and Wil Wheaton.
Sheldon's tenuous relationship with renowned scientist STEPHEN HAWKING is threatened by a game of "Words with Friends," while Pennysecretly enrolls in a class at the local college.
The gang celebrates Halloween at Stuart's comic book store. Meanwhile Leonard and Penny discover a new spark in their relationshipwhen he seduces her with science.