The Big Bang Theory
About the Show
Arch-nerds Leonard and Sheldon may know more than their fair share about subatomic particles, but when it comes to people in general, and women in particular, they're absolutely clueless...
Series 6 Summary
The sixth series of the US comedy about a group of highly intelligent but socially clueless scientists and their savvy neighbour Penny.
Episode 1 - The Date Night Variable
Howard gets caught in an argument between his mum and Bernadette while at the International Space Station. Raj is feeling lonely so Sheldon invites him along to his second anniversary date with Amy.
Episode 2 - The Decoupling Fluctuation
Sheldon intervenes when he learns that Penny is thinking about breaking up with Leonard, but he is hampered by his inability to keep a secret. Meanwhile, in space, Howard is being picked on by the other astronauts.
Episode 3 - The Higgs Boson Observation
Amy is jealous when Sheldon hires an attractive female assistant named Alex. However, it turns out that Alex is more interested in Leonard, which makes Penny feel threatened.
Meanwhile, Howard discovers that his return from space has been delayed by a week and the pressure begins to take its toll on his mind.
Episode 4 - The Re-entry Minimization
Wolowitz is disappointed when he doesn't receive a hero's welcome on his return from space. Bernadette is out of action with a heavy cold, and his mother is occupied with her dentist.
Koothrappali has a new best friend, while Sheldon, Amy, Leonard and Penny are deeply involved in an ultra-competitive games night. Will Wolowitz ever get the recognition he deserves as an astronaut?
Episode 5 - The Holographic Excitation
The gang celebrates Halloween with a fancy dress party at Stuart's comic book shop, but Sheldon and Amy can't agree about which costumes to wear.
Leonard and Penny get a new romantic spark in their relationship when she visits him at his laboratory.
Howard just can't stop talking about his trip to space, much to the irritation of his friends, and it takes a word from astronaut Buzz Aldrin (guest starring as himself) to get his feet back on the ground.
Episode 6 - The Extract Obliteration
Sheldon is excited when Stephen Hawking (guest starring as himself in a vocal cameo) agrees to play Words with Friends with him online. But Hawking's not happy when Sheldon starts to dominate the game.
Meanwhile, Penny signs up for a class at community college but is reluctant to tell Leonard about it.
Episode 7 - The Habitation Configuration
Amy gets upset when Sheldon fails to defend her in an argument with Wil Wheaton during the filming of a new episode of Fun with Flags.
Bernadette pressures Howard to move the rest of his possessions out of his mother's house and into her flat.
Star Trek: The Next Generation actors Wil Wheaton and LeVar Burton guest star as themselves.
Episode 8 - The 43 Peculiarity
The guys notice that Sheldon disappears for 20 minutes right after lunch every day. Filled with curiosity, they attempt to follow him and work out what on earth he's been doing.
Penny befriends a British student in her class and they start exchanging text messages, but a jealous Leonard tries to discourage the friendship.
Episode 9 - The Parking Spot Escalation
When non-driver Sheldon finds out that his unused parking space at the university has been reallocated to Howard, he feels undermined.
Howard doesn't see the problem in using something that his friend doesn't need and the two fall out.
As their disagreement escalates, each begins to steal items that are not being used at the time from the other, while Amy and Bernadette gradually get drawn into the dispute.
Episode 10 - The Fish Guts Displacement
Sheldon begrudgingly takes care of Amy when she is sick, but she loves the extra attention so much that she is still pretending to be ill long after her recovery is complete.
Bernadette arranges for Howard to go on a fishing trip with her macho father, hoping that they will bond. However, Howard has no idea how to fish and is forced to ask Penny for advice on how to act in a manly way.
Episode 11 - The Santa Simulation
Sheldon reveals painful memories of Christmas past when Leonard persuades him to join in with a seasonal game of Dungeons & Dragons.
When Raj joins Penny, Bernadette and Amy on a ladies' night out, they attempt to find the perfect girl for him after he reveals the truth about some of his crushes.
Episode 12 - The Egg Salad Equivalency
When Sheldon's assistant Alex starts flirting with Leonard, Sheldon is displeased and decides to have a word with her about it.
Unfortunately, his comments are so inappropriate that he is accused of sexual harassment and sent to the university's human resources department, where he ends up dragging Leonard, Raj and Howard into trouble too.
Episode 13 - The Bakersfield Expedition
The guys take a road trip to a comic book convention in Bakersfield and visit a location where several episodes of Star Trek were filmed.
As they stage a photo opportunity dressed as their favourite sci-fi characters, Leonard's car is stolen, leaving them stranded.
Meanwhile, the girls visit Stuart's comic book shop in an effort to understand their partners' fixation on the subject.
Episode 14 - The Cooper/Kripke Inversion
Sheldon is outraged when the university forces him to work on the same project as his nemesis, Barry Kripke.
When the two of them examine each other's research, Sheldon discovers that Kripke's work is much more advanced than his own and he suffers a major crisis of confidence.
Howard and Raj spend a lot of money on personalised action figures modelled on their own likeness, but when the dolls arrive the guys are disappointed by their appearance.
Episode 15 - The Spoiler Alert Segmentation
Sheldon and Leonard have a row when Sheldon gives away the ending of the Harry Potter book that Leonard is reading.
As a result, Leonard attempts to move in with Penny, despite the fact that she isn't ready for this big step. Amy then takes the opportunity to persuade Sheldon that she should start living with him, much to his alarm.
Meanwhile, when Howard and Bernadette take a trip to Las Vegas, Raj is persuaded to keep an eye on Mrs Wolowitz during their absence.
Episode 16 - The Tangible Affection Proof
Leonard tries to give Penny the perfect Valentine's Day treat by taking her to a nice restaurant with Howard and Bernadette, but the evening takes a turn for the worse when they spot Penny's ex-boyfriend and his new date.
Annoyed at being forced to celebrate Valentine's Day when he hates it, Sheldon delegates the task of buying Amy's gift to his assistant, Alex.
Meanwhile, as they are not in relationships, Raj and Stuart throw a party for singles at the comic book shop.
Episode 17 - The Monster Isolation
After a terrible date with Lucy, the girl he met at Stuart's comic book shop singles party, Raj vows never to leave his flat or interact with another woman again. Leonard, Howard and Bernadette attempt to cheer him up.
Sheldon asks Penny to help him record a new episode of Fun with Flags, and her useful tips leave him deeply impressed by her acting skills.
Episode 18 - The Contractual Obligation Implementation
When Leonard, Sheldon and Howard are forced to volunteer for a university committee, they join one that advances the cause of women in science and arrange to speak to school girls about their future careers.
Raj plans a date with Lucy that won't aggravate her problems with social anxiety, while Penny, Amy and Bernadette abandon their jobs for a day trip to Disneyland.
Episode 19 - The Closet Reconfiguration
When Howard and Bernadette get Sheldon to organise their untidy closet, Sheldon finds an unopened letter from Howard's long-absent father, who abandoned his family years earlier.
This leaves Howard in a quandary as he struggles to decide whether to confront his past and read the letter or just destroy it.
Meanwhile, in an effort to enjoy a more 'grown-up' social life, Leonard and Penny throw a sophisticated cocktail party at their flat.
Episode 20 - The Tenure Turbulence
When a tenured position becomes available at the university, Leonard, Sheldon, Raj and Kripke are all keen to apply for it.
As the competition heats up between them, they learn that HR manager Janine Davis is on the tenure committee, but their constant attempts to impress her and win her approval just end up causing irritation and offence.
Episode 21 - The Closure Alternative
Amy employs a series of exercises to cure Sheldon of his compulsion to complete every task without fail and seek closure for every incident.
Raj reads Lucy's blog and is dismayed to discover that she has written about him and referred to his feminine personality traits. On their next date, he starts to over-compensate and attempts to act in a very masculine way.
Penny frets that she isn't passionate enough about anything in her life.
Episode 22 - The Proton Resurgence
When Leonard and Sheldon find out that Professor Proton, the host of a TV science show they watched as children, can be booked for private parties, they hire him to come to their flat and entertain them.
Raj asks Howard and Bernadette to look after his dog for the weekend, but the couple are thrown into a panic when the hound goes missing.
Episode 23 - The Love Spell Potential
When the girls' planned trip to Las Vegas falls through, the guys invite them to a Dungeons & Dragons date night, which results in Sheldon and Amy's relationship taking an unexpected turn...
Episode 24 - The Bon Voyage Reaction
Leonard is offered an exciting job opportunity that will keep him out of the country for several months.
Penny does her best to support Leonard's ambitions, whereas Sheldon is jealous of his friend and discourages him from accepting the post.
Meanwhile, Raj pushes the boundaries of his relationship with Lucy, putting their romance in jeopardy.
The Big Bang Theory synopsis
Arch-nerds Leonard and Sheldon may know more than their fair share about subatomic particles, but when it comes to people in general, and women in particular, they're absolutely clueless...Episode Guide >
Next on TV
After Sheldon bans Penny from the apartment for numerous minor infractions, she decides to retaliate. Her plan involves a telephone, and Sheldon's mother.