The Big Bang Theory

    • Episode 1 - The Bad Fish Paradigm

      Penny opens up to a reluctant Sheldon after a less-than-stellar first date with Leonard, placing him in the uncomfortable position of having to keep a secret.

    • Episode 2 - The Codpiece Topology

      Seeing Penny out on a date with another guy sends a distressed Leonard rushing back to Leslie Winkle, much to Sheldon's dismay

    • Episode 3 - The Barbarian Sublimation

      Penny becomes addicted to an online game based on the world of Conan the Barbarian and persistently pesters Sheldon for advice.

    • Episode 4 - The Griffin Equivalency

      Full of confidence after being named one of People Magazine's '30 to Watch under 30', Raj hits on Penny and becomes impossibly arrogant

    • Episode 5 - The Euclid Alternative

      When Leonard can't drive Sheldon to and from work, the friends stage an intervention to overcome Sheldon's fear of getting behind the wheel

    • Episode 6 - The Cooper-Nowitzki Theorem

      Sheldon's friends are mystified when a younger student is attracted to him, but her intense devotion soon becomes too much

    • Episode 7 - The Panty Piñata Polarization

      After Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate. Her plan involves a telephone, and Sheldon's mother.

    • Episode 8 - The Lizard-Spock Expansion

      A girl Wolowitz has a major crush on falls for Leonard, despite Wolowitz's elaborate attempts to woo her - including an abortive joyride on the Mars Rover.

    • Episode 9 - The White Asparagus Triangulation

      Sheldon is delighted that Leonard finally has a girlfriend matching his high standards. Perhaps a little too delighted.

    • Episode 10 - The Vartabedian Conundrum

      Leonard goes to Penny for help when his relationship with Stephanie takes off faster than he'd like, but will he choose to act on her advice?

    • Episode 11 - The Bath Item Gift Hypothesis

      At Christmas, Leonard's handsome colleague starts dating Penny, while Sheldon's obsession with gift-giving etiquette torments his friends

    • Episode 12 - The Killer Robot Instability

      Kripke challenges the boys to a robot duel, while Howard is hurt when Penny reveals what she thinks about his behaviour towards women

    • Episode 13 - The Friendship Algorithm

      Sheldon develops a scientific procedure for making friends when he discovers that Kripke has control of a new supercomputer at the university

    • Episode 14 - The Financial Permeability

      When Sheldon lends Penny some money, it brings her ex-boyfriend Kurt back into her life, with negative consequences for the gang

    • Episode 15 - The Maternal Capacitance

      A disastrous visit from Leonard's mother Beverly has the unexpected side-effect of bringing Leonard and Penny closer together

    • Episode 16 - The Cushion Saturation

      A game of paintball leads to a squabble when Penny accidentally shoots paint at one of Sheldon's cushions. Romance blossoms between Howard and Leslie.

    • Episode 17 - The Terminator Decoupling

      Leonard, Sheldon, Howard and Raj discover that beautiful sci-fi actress Summer Glau is on board their train to San Francisco

    • Episode 18 - The Work Song Nanocluster

      Penny's home-based business selling hair barrettes - her 'Pennyblossoms' - gets out of hand when a caffeine-high Sheldon takes charge

    • Episode 19 - The Dead Hooker Juxtaposition

      Penny develops a rivalry with sexy new female neighbour Alicia, who threatens to steal the boys' attention and become the 'new Penny'

    • Episode 20 - The Hofstadter Isotope

      Leonard is devastated when Stuart from the comic book shop chats Penny up. Even worse, she doesn't mind, so Sheldon tries to scupper the budding romance.

    • Episode 21 - The Vegas Renormalisation

      Leonard and Raj take a heartbroken Howard to Las Vegas, home of slots, shrimp, and high-class hookers. Sheldon, meanwhile, is locked out of his apartment and forced to bunk with Penny.

    • Episode 22 - The Classified Materials Turbulence

      Things begin to look up for Leonard when Penny makes a surprising revelation on her second date with Stuart

    • Episode 23 - The Monopolar Expedition

      Leonard and Penny reconsider their feelings for each other, but then Leonard decides to spend the summer working at the North Pole - on a mission led by Sheldon.