Episode 1 | The Hofstadter Insufficiency

Sheldon and Penny bond over missing Leonard. Howard tries to help Raj get over his breakup with Lucy. Amy and Bernadette take a trip together to a biology convention.

Episode 2 | The Deception Verification

Sheldon feels betrayed when Leonard returns from the North Sea and wants to spend his time with Penny instead of him. Howard's latest foray into helping his mother has some disastrous side effects.

Episode 3 | The Scavenger Vortex

The gang get competitive when they are forced to take part in Raj's scavenger hunt.

Episode 4 | The Raiders Minimization

Sheldon gets mad at Amy for ruining one of his favorite movies, Raj and Stuart try to make their online dating profiles more appealing, and Leonard tries to play the sympathy card with Penny.

Episode 5 | The Workplace Proximity

After a fight with Bernadette, Howard ends up on Raj's couch. Sheldon and Amy clash when Amy takes a job at the university.

Episode 6 | The Romance Resonance

Howard plans something special to celebrate the anniversary of his first date with Bernadette. Sheldon is conflicted when he makes a major scientific breakthrough but some details have to be corrected.

Episode 7 | The Proton Displacement

Sheldon seeks payback when Arthur "Professor Proton" Jeffries asks Leonard for help on a project instead of him. Raj gets upset at Howard for crashing his night with the girls.

Episode 8 | The Itchy Brain Simulation

Sheldon demands Leonard make up for a mistake from their past. Penny confronts Raj's ex-girlfriend, Lucy.

Episode 9 | The Thanksgiving Decoupling

The gang spend Thanksgiving at Mrs. Wolowitz's house. Howard tries to bond with his father-in-law, and a mistake from Penny's past comes back to haunt her.

Episode 10 | The Discovery Dissipation

Leonard has to deal with the fallout of disproving Sheldon's new scientific discovery. Raj spends a week at Howard and Bernadette's apartment.

Episode 11 | The Cooper Extraction

While Sheldon is at home in Texas, the rest of the gang decorate for Christmas and think about how much he has affected their lives.

Episode 12 | The Hesitation Ramification

After Leonard tries to help Penny following a failed role on a TV show, she makes an important decision. Meanwhile, Raj and Stuart try to practice their social skills, and Sheldon navigates the intricacies of being funny.

Episode 13 | The Occupation Recalibration

Sheldon tries to relax after he is forced to take a vacation. Leonard struggles to be supportive of Penny after she quits her job. Amy receives unwanted attention from a co-worker. Bernadette seeks Stuart's help in replacing one o...

Episode 14 | The Convention Conundrum

When the guys can't get hold of any Comic-Con tickets, Sheldon tries to hold his own convention and ends up spending a wild night with James Earl Jones. Meanwhile, the girls try to feel more mature by going to a fancy hotel for tea.

Episode 15 | The Locomotive Manipulation

Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine's Day. Leonard and Penny take Raj's dog to the vet when she accidentally eats some chocolate.

Episode 16 | The Table Polarization

Leonard's purchase of a dining room table causes Sheldon to reevaluate the changes in his life. Meanwhile, Howard is offered a chance to go back to space and Bernadette struggles with whether or not to encourage him.

Episode 17 | The Friendship Turbulence

After arguing with Sheldon, Howard tries to make amends by taking him to NASA headquarters in Houston. Penny has second thoughts about quitting her waitressing job when her car dies. Amy gets involved in trying to find Raj a date.

Episode 18 | The Mommy Observation

When Sheldon visits his mother in Houston, he is forced to confront a new reality. Back in Pasadena, the rest of the gang reluctantly take part in Raj's Murder Mystery party.

Episode 19 | The Indecision Amalgamation

While Raj is wracked with guilt when he tries to date Lucy and Emily at the same time, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is torn trying to choose between two gaming systems.

Episode 20 | The Relationship Diremption

Penny tries to help Sheldon when he reconsiders his "relationship" with String Theory. During a dinner with Howard and Bernadette, Raj discovers Howard once embarrassed himself on a date with Emily.

Episode 21 | The Anything Can Happen Recurrence

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

Episode 22 | The Proton Transmogrification

As the gang celebrate Star Wars Day, Sheldon has difficulty dealing with the recent death of Arthur "Professor Proton" Jeffries.

Episode 23 | The Gorilla Dissolution

Penny gets fired from her movie and takes a serious look at her life. Raj sees Emily on a date with another man at the movies. Howard and Bernadette have to take care of his mother after she breaks her leg.

Episode 24 | The Status Quo Combustion

Sheldon gets upset about his career, the destruction of the comic book store and Leonard and Penny's future living arrangements. Howard and Bernadette struggle to keep hold of a caregiver for Mrs. Wolowitz.