Episode 1 | The Date Night Variable

Raj crashes Sheldon and Amy's second anniversary and interferes in Leonard and Penny's relationship. Howard gets caught in the middle of an argument between Bernadette and his mother.

Episode 2 | The Decoupling Fluctuation

Penny continues to have doubts about her relationship with Leonard. Meanwhile, Howard becomes the target of practical jokes on the space station.

Episode 3 | The Higgs Boson Observation

When Sheldon hires a female grad student to assist him, a jealous Amy asks Penny to help her spy on them. On the space station, Howard begins behaving erratically.

Episode 4 | The Re-Entry Minimization

Howard is offended when his return from space is met with little fanfare. Penny and Amy take on Sheldon and Leonard during game night.

Episode 5 | The Holographic Excitation

While Raj plans Stuart's Halloween party at the comic book store, Howard annoys the rest of the gang by constantly talking about space, and Penny tries to take more of an interest in Leonard's work.

Episode 6 | The Extract Obliteration

Penny enrolls in a college class and keeps it a secret from Leonard. Sheldon causes conflict with Dr. Stephen Hawking over an online game.

Episode 7 | The Habitation Configuration

Howard makes a decision whether or not to move out of his mother's house, while Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.

Episode 8 | The 43 Peculiarity

Leonard feels threatened after hearing about Penny's study partner at school, while Howard and Raj become determined to find out one of Sheldon's secrets.

Episode 9 | The Parking Spot Escalation

The gang are drawn into a fight between Howard and Sheldon over Sheldon's vacant parking spot at the university.

Episode 10 | The Fish Guts Displacement

Howard tries to bond with Bernadette's father during a fishing trip. When Sheldon is obligated to take care of a sick Amy, she finds ways to take advantage of the situation.

Episode 11 | The Santa Simulation

The girls take Raj out to a nightclub to find him a date. A game of Dungeons and Dragons rekindle old memories of Santa for Sheldon.

Episode 12 | The Egg Salad Equivalency

When Penny finds out Alex has a crush on Leonard, Sheldon gets himself and the rest of the guys in trouble with Human Resources whilst trying to solve the problem.

Episode 13 | The Bakersfield Expedition

The guys are stranded in the middle of nowhere when Leonard's car is stolen on the way to the Bakersfield Comic-Con. Back home, the girls try to figure out why the guys are so fascinated with comic books.

Episode 14 | The Cooper/Kripke Inversion

Sheldon is forced to work with Kripke on a project and must concoct an elaborate lie when he can't hold up his end of the work. Howard and Raj get superhero figurines made of themselves.

Episode 15 | The Spoiler Alert Segmentation

Leonard moves in with Penny after a fight with Sheldon, which causes Amy to want to move in with Sheldon. Meanwhile, Raj has a frightening experience with Howard's mother.

Episode 16 | The Tangible Affection Proof

Sheldon gets Alex to buy a Valentine's Day gift for Amy. Leonard, Penny, Howard and Bernadette have a disastrous dinner together. Raj and Stuart host a "Lonely People" party at the comic book store.

Episode 17 | The Monster Isolation

Raj falls apart after his date sneaks out on him, and Sheldon reluctantly returns the favor after Penny helps him out with his "Fun With Flags" program.

Episode 18 | The Contractual Obligation Implementation

Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland. Raj devises a date for Lucy that fixes their social anxiety problems.

Episode 19 | The Closet Reconfiguration

Howard becomes upset when Sheldon finds a letter from his estranged father whilst cleaning out his and Bernadette's closet.

Episode 20 | The Tenure Turbulence

Leonard, Sheldon, Raj and Kripke battle for tenure at the university.

Episode 21 | The Closure Alternative

Amy tries to help a depressed Sheldon find closure when one of his favorite TV shows is canceled. Raj becomes paranoid when he finds Lucy's blog.

Episode 22 | The Proton Resurgence

Bernadette and Howard offer to watch Raj's dog and live to regret it. Leonard and Sheldon hire their favorite childhood star to make an appearance.

Episode 23 | The Love Spell Potential

A date between Raj and Lucy takes both of them out of their comfort zones. After a trip to Las Vegas goes awry, the girls join in on a Dungeons and Dragons game, which causes Amy and Sheldon to re-evaluate their relationship.

Episode 24 | The Bon Voyage Reaction

Penny is thrown for a loop when Leonard is offered a job overseas, but the news is an even bigger shock to Sheldon. Raj and Lucy's relationship comes to a crossroad.