Episode 1 | The Skank Reflex Analysis

The gang deal with the fallout from Penny and Raj's night together.

Episode 2 | The Infestation Hypothesis

Amy gets inadvertently caught in the middle of a fight between Sheldon and Penny over a chair. Leonard tries to add some spice to his long-distance relationship with Priya.

Episode 3 | The Pulled Groin Extrapolation

Leonard accompanies Amy to a colleague's wedding. Howard tries to convince Bernadette to live with his mother after they get married.

Episode 4 | The Wiggly Finger Catalyst

Penny sets up Raj with a deaf friend, not knowing that she's actually a gold digger, and Sheldon decides to let his minor decisions rest on the roll of the dice.

Episode 5 | The Russian Rocket Reaction

Sheldon takes offense when Leonard wants to attend a party with Wil Wheaton, while Bernadette tries to block Howard's opportunity to go into outer space.

Episode 6 | The Rhinitis Revelation

Sheldon gets upset when his mother comes to visit but refuses to cook for him and attend physics lectures.

Episode 7 | The Good Guy Fluctuation

Sheldon tries to get into the spirit of Halloween by trying to scare the guys after they prank him. Leonard seeks Penny's advice when an attractive comic book artist takes an interest in him.

Episode 8 | The Isolation Permutation

Amy is hurt when Penny and Bernadette go bridesmaid dress shopping without her, so she turns to a reluctant Sheldon for comfort.

Episode 9 | The Ornithophobia Diffusion

Sheldon tries to overcome his fear of birds, while Leonard and Penny attempt to hang out together strictly as friends.

Episode 10 | The Flaming Spittoon Acquisition

When Stuart asks Amy on a date, Sheldon considers having a more serious relationship with her. Meanwhile, the guys become obsessed with a new card game involving Wild West heroes and witches.

Episode 11 | The Speckerman Recurrence

Leonard confronts the man who bullied him in high school, while Penny realizes she did her fair share of tormenting in the past.

Episode 12 | The Shiny Trinket Maneuver

Penny helps Sheldon work on his relationship with Amy when he trivializes one of her accomplishments. Howard is irked by Bernadette's dislike of children.

Episode 13 | The Recombination Hypothesis

Leonard and Penny contemplate reviving their romantic relationship.

Episode 14 | The Beta Test Initiation

Leonard and Penny develop a system to ensure their dates go smoothly. Raj finally finds a woman he can talk to - the virtual assistant on his mobile phone.

Episode 15 | The Friendship Contraction

Leonard signs out of his roommate agreement, reducing himself and Sheldon to mere acquaintances, while Howard tries to think of a cool astronaut nickname for himself.

Episode 16 | The Vacation Solution

When the university forces Sheldon to use vacation days, he decides to hang out in Amy's lab. Howard becomes upset when he hears Bernadette wants him to sign a prenuptial agreement.

Episode 17 | The Rothman Disintegration

Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.

Episode 18 | The Werewolf Transformation

Sheldon wreaks havoc when he tries to get a haircut from his regular barber, who is ill. Howard runs into a few problems with astronaut training.

Episode 19 | The Weekend Vortex

Sheldon has to choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

Episode 20 | The Transporter Malfunction

Raj gets quite a surprise when he asks his parents to set him up on a date. Penny buys Leonard and Sheldon a pair of Star Trek keepsake collectibles.

Episode 21 | The Hawking Excitation

Sheldon uses any and all means to meet his hero, Dr. Stephen Hawking.

Episode 22 | The Stag Convergence

The guys throw Howard a bachelor party, and some embarrassing details about his life get posted on the Internet.

Episode 23 | The Launch Acceleration

NASA cancel, and later reinstate Howard's mission into space, coinciding with his wedding. Leonard inadvertently jeopardizes his relationship with Penny.

Episode 24 | The Countdown Reflection

As Howard prepares for his mission into space, flashbacks show the recent events leading up to his and Bernadette's wedding.