Episode 1 | The Locomotion Interruption

Sheldon's trip comes to an end when he is robbed, Penny interviews for a job at Bernadette's company, and Howard is weirded out by his mother's relationship with Stuart.

Episode 2 | The Junior Professor Solution

Sheldon is forced to teach a class as a Junior Professor. Meanwhile, Amy plays both sides when tension arises between Penny and Bernadette.

Episode 3 | The First Pitch Insufficiency

Howard becomes nervous after NASA asks him to throw out the first pitch at a Los Angeles Angels game. Meanwhile, Leonard and Penny try to prove Sheldon wrong when he says that he and Amy have a 'superior' relationship.

Episode 4 | The Hook-up Reverberation

Raj's honesty about his past comes back to haunt him after Emily takes a dislike to Penny. Meanwhile, the guys consider investing in the comic book store.

Episode 5 | The Focus Attenuation

The girls head to Las Vegas, while the guys try to invent something cool, but only come up with new ways to procrastinate.

Episode 6 | The Expedition Approximation

Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a steam tunnel. Meanwhile, Leonard and Penny seek advice from Howard and Bernadette when they argue a...

Episode 7 | The Misinterpretation Agitation

The guys befriend one of Penny's clients when he shows up at her apartment. Meanwhile, Bernadette gets upset when Amy torpedoes an article about her for a local magazine.

Episode 8 | The Prom Equivalency

The girls decide to re-enact their high school proms with the guys. While Sheldon feels under pressure to commit to his relationship with Amy, Howard worries about who Stuart will bring as his date.

Episode 9 | The Septum Deviation

Sheldon panics when Leonard announces he has to go into the hospital for surgery. Raj discovers his parents have divorced.

Episode 10 | The Champagne Reflection

While Sheldon retires "Fun With Flags", Leonard, Howard and Raj look for something significant in a dead professor's research, and Bernadette finds out what her colleagues really think of her.

Episode 11 | The Clean Room Infiltration

Amy hosts a traditional Victorian Christmas Eve dinner as Raj's father comes to visit, while the guys try to shoo out a bird they let into the university clean room.

Episode 12 | The Space Probe Disintegration

Raj worries a probe he designed will not work in outer space, while Leonard and Sheldon go shopping with Penny and Amy.

Episode 13 | The Anxiety Optimization

When Sheldon becomes stuck in a rut with his work, the gang try to help him by raising his stress levels. Howard teases Raj with a game called "Emily or Cinnamon."

Episode 14 | The Troll Manifestation

Leonard and Sheldon defend themselves against criticism from an online bully, while the girls confront embarrassing moments from their pasts.

Episode 15 | The Comic Book Store Regeneration

Howard receives some shocking news as everyone prepares for the re-opening of the comic book store. Meanwhile, Penny tries to teach Sheldon how to "let it go," but can't follow her own advice when she learns something infuriating ...

Episode 16 | The Intimacy Acceleration

Sheldon and Penny agree to participate in an unusual experiment. Leonard, Amy, Raj and Emily spend the evening trying to escape a room with a "zombie". Howard and Bernadette run into trouble at the airport after returning from Mrs...

Episode 17 | The Colonization Application

A trip to the pet store ends in a fight after Amy learns Sheldon has applied for a one-way mission to colonize Mars. Meanwhile, Leonard surprises Penny with a very "adult" purchase, and Raj gets into trouble when he snoops around ...

Episode 18 | The Leftover Thermalization

Tension arises when a magazine fails to mention Leonard in an article about the paper he co-wrote with Sheldon, and a blackout at Mrs. Wolowitz's home leads to a final family dinner in her honor.

Episode 19 | The Skywalker Incursion

When Leonard and Sheldon are invited to speak at UC Berkeley, they take a detour to try and meet one of their idols. Meanwhile, while cleaning out Mrs. Wolowitz's house, a ping pong battle ensues when Howard and Bernadette argue o...

Episode 20 | The Fortification Implementation

Howard meets the half-brother he never knew he had. Penny is invited to appear on Wil Wheaton's podcast.

Episode 21 | The Communication Deterioration

When Raj is asked to create a message on the off chance a NASA mission discovers alien life, the guys fight over what he should do, while Penny contemplates returning to acting.

Episode 22 | The Graduation Transmission

Howard questions his engineering abilities when he and Sheldon can't get a toy drone to fly. A cancelled flight nearly prevents Leonard from giving the commencement address at his former high school. Raj pits his parents against e...

Episode 23 | The Maternal Combustion

Personalities collide when Leonard and Sheldon's mothers meet for the first time. Bernadette reaches her limit with Howard and Stuart.

Episode 24 | The Commitment Determination

As Sheldon presses Leonard and Penny to set a wedding date, he encounters major changes in his relationship with Amy. Meanwhile, Raj wonders if he should break up with Emily, and Howard and Bernadette struggle to ask Stuart to mov...