The Big Bang Theory

Sheldon and Penny spend quality time together sharing intimate secrets and Wolowitz helps Raj get over his ex-girlfriend.

Leonard's friendship with Sheldon is put to the test. Wolowitz's relationship with his mother causes an unusual threat to his masculinity.

When the entire gang competes in a scavenger hunt designed by Raj, it brings out the best - and worst - in everyone.

Sheldon wants revenge on Amy; Leonard gets Penny to do anything; Stuart and Raj make online dating profiles.

Amy starts working at Caltech which causes friction with Sheldon and the Wolowitzes have a big fight.

Sheldon's latest scientific breakthrough leaves him feeling like a fraud, and a romantic gesture causes Penny to up her game.

When Professor Proton asks Leonard for help with an experiment, Sheldon retaliates by befriending Proton's rival, Bill Nye.

When a mistake comes to light, Sheldon makes Leonard walk a mile in his shoes; Penny decides to confront Raj's ex.

When the gang decides to spend Thanksgiving at Mrs. Wolowitz's house, Sheldon protests; Leonard and Penny deal with an error from her past.

Amy and Leonard try to help Sheldon deal with his shame, and Raj stays with Bernadette and Howard for a week.

While Sheldon is away, everyone gathers to decorate the apartment Christmas tree, and they each realize how much he has changed their lives.

Penny asks Leonard a bold relationship question, Sheldon tries to learn how to be funny, and Raj must work on his game before talking to girls.

Sheldon tries to relax after he is forced to take a vacation, and Leonard struggles to be supportive of Penny after she quits her job.

With the guys acting like teenagers about Comic-Con tickets, the girls decide they're going to have a more grown up afternoon.

Love is in the air when Sheldon and Amy join Howard and Bernadette for a trip to wine country. Meanwhile, Leonard and Penny must rush Raj's dog to the vet.

Leonard's purchase of a dining room table nearly causes Sheldon to break up with Amy, while Howard is offered a chance to return to space again.

After the insults fly, Bernadette tries to broker the peace between Wolowitz and Sheldon. Meanwhile, Penny is offered an embarrassing movie role, and Raj asks Amy to write to a woman on his behalf.

While Raj is having a murder mystery party in Pasedena, Howard and Sheldon get their tour of NASA in Houston and then drop in unannounced at Sheldon's mother who was not expecting company.

While Raj is wracked with guilt when he tries to date two women at once, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is torn between two gaming systems.

Sheldon faces a personal crisis after deciding he's wasting his time with string theory. Meanwhile, a double date between Raj, Emily and the Wolowitzes ends in embarrassment for Howard.

When Sheldon tries to be spontaneous, it leads to unexpected friction between Penny, Amy and Bernadette. Meanwhile, Raj seeks Howard's help in preparing for a date with Emily.

Professor Proton helps Sheldon cope with grief while Leonard turns a relationship milestone into a competition with Penny. Meanwhile, Amy and Bernadette make a "Star Wars Day" gift for the guys.

A bad day causes Penny to reevaluate her life choices - including Leonard. Howard and Bernadette struggle to care for Mrs. Wolowitz.

Sheldon is forced to confront an uncertain future and considers a major move. Meanwhile, Raj and Emily take things to the next level.