The Proton Transmogrification: Sheldon struggles to process his feelings of grief when his idol Professor Proton passes away. The gang gather to celebrate Star Wars Day. (S7 Ep22) [AD,S]
The Gorilla Dissolution: Penny re-evaluates her life, including taking a big step with Leonard, while Howard and Bernadette struggle to look after Mrs Wolowitz. (S7 Ep23) [AD,S]
The Status Quo Combustion: With potential changes affecting different aspects of his personal and professional life, Sheldon is forced to confront an uncertain future. (S7 Ep24) [AD,S]
The Proton Transmogrification: Sheldon struggles to process his feelings of grief when his idol Professor Proton passes away. The gang gather to celebrate Star Wars Day. (S7 Ep22) [AD,S]
The Gorilla Dissolution: Penny re-evaluates her life, including taking a big step with Leonard, while Howard and Bernadette struggle to look after Mrs Wolowitz. (S7 Ep23) [AD,S]
The Status Quo Combustion: With potential changes affecting different aspects of his personal and professional life, Sheldon is forced to confront an uncertain future. (S7 Ep24) [AD,S]
The Anxiety Optimization: When Sheldon gets stuck in a rut with his research, he asks his friends to cure his mental block by raising his stress levels. (S8 Ep13) [AD,S]
The Troll Manifestation: Leonard and Sheldon co-publish a physics paper but are forced to defend themselves against negative comments from an online critic. (S8 Ep14) [AD,S]
The Comic Book Store Regeneration: The gang prepare for the reopening of Stuart's comic book shop. Penny teaches Sheldon to 'let it go' when he is irritated. (S8 Ep15) [AD,S]
The Anxiety Optimization: When Sheldon gets stuck in a rut with his research, he asks his friends to cure his mental block by raising his stress levels. (S8 Ep13) [AD,S]
The Troll Manifestation: Leonard and Sheldon co-publish a physics paper but are forced to defend themselves against negative comments from an online critic. (S8 Ep14) [AD,S]
The Grasshopper Experiment: Raj panics when his parents arrange a blind date for him. But he discovers that he can talk to her - after a few drinks. (S1 Ep8) [AD,S]
The Comic Book Store Regeneration: The gang prepare for the reopening of Stuart's comic book shop. Penny teaches Sheldon to 'let it go' when he is irritated. (S8 Ep15) [AD,S]
The Cooper-Hofstadter Polarization: Sheldon and Leonard fall out when they're asked to collaborate at a physics conference. Penny tries to help but just makes things worse. (S1 Ep9) [AD,S]
The Tenant Disassociation: Leonard competes with Sheldon to become president of the tenants' association. Howard and Raj find a drone in the back garden. (S11 Ep19) [AD,S]
The Reclusive Potential: A brilliant scientist invites Sheldon to his isolated cabin, and Leonard, Raj and Howard go along for the trip. (S11 Ep20) [AD,S]
The Tenant Disassociation: Leonard competes with Sheldon to become president of the tenants' association. Howard and Raj find a drone in the back garden. (S11 Ep19) [AD,S]
The Reclusive Potential: A brilliant scientist invites Sheldon to his isolated cabin, and Leonard, Raj and Howard go along for the trip. (S11 Ep20) [AD,S]
The Locomotion Interruption: Leonard and Amy take an impromptu road trip to Arizona to pick up Sheldon when his epic railway journey ends in chaos. Penny has an interview. (S8 Ep1) [AD,S]
The Junior Professor Solution: When Sheldon has to teach a course at the university, Howard enrols in his class. Tension brews between Penny and Bernadette. (S8 Ep2) [AD,S]
The First Pitch Insufficiency: Howard's nervous when NASA ask him to throw the first pitch at a baseball game. Sheldon claims his and Amy's relationship is the best in the gang. (S8 Ep3) [AD,S]
The Locomotion Interruption: Leonard and Amy take an impromptu road trip to Arizona to pick up Sheldon when his epic railway journey ends in chaos. Penny has an interview. (S8 Ep1) [AD,S]
The Junior Professor Solution: When Sheldon has to teach a course at the university, Howard enrols in his class. Tension brews between Penny and Bernadette. (S8 Ep2) [AD,S]
The First Pitch Insufficiency: Howard's nervous when NASA ask him to throw the first pitch at a baseball game. Sheldon claims his and Amy's relationship is the best in the gang. (S8 Ep3) [AD,S]
The Intimacy Acceleration: When the gang hear about an experiment designed to make participants fall in love, Sheldon and Penny put it to the test as a joke. (S8 Ep16) [AD,S]
The Colonization Application: Amy learns that Sheldon has applied to take part in a one-way mission to colonise Mars. Leonard surprises Penny with a gift. (S8 Ep17) [AD,S]
The Leftover Thermalization: A power cut at Mrs Wolowitz's house defrosts the last meal she prepared before her death, so the gang consume it in her honour. (S8 Ep18) [AD,S]
The Intimacy Acceleration: When the gang hear about an experiment designed to make participants fall in love, Sheldon and Penny put it to the test as a joke. (S8 Ep16) [AD,S]
The Colonization Application: Amy learns that Sheldon has applied to take part in a one-way mission to colonise Mars. Leonard surprises Penny with a gift. (S8 Ep17) [AD,S]
The Loobenfeld Decay: Leonard and Sheldon each tell a lie to avoid going to see Penny singing on stage in a production of Rent, but Sheldon's fib gets out of control. (S1 Ep10) [AD,S]
The Leftover Thermalization: A power cut at Mrs Wolowitz's house defrosts the last meal she prepared before her death, so the gang consume it in her honour. (S8 Ep18) [AD,S]
The Pancake Batter Anomaly: Penny volunteers to nurse Sheldon when he's sick. But his friends, who know how miserable he is when he's ill, stay well away. (S1 Ep11) [AD,S]
The Comet Polarization: Sheldon isn't pleased by the comic book shop's new-found popularity. Raj tries to take the credit for Penny's astronomical discovery. (S11 Ep21) [AD,S]
The Monetary Insufficiency: Sheldon goes to Las Vegas to try to win money for science. Penny and Bernadette take Amy shopping for a wedding dress. (S11 Ep22) [AD,S]
The Comet Polarization: Sheldon isn't pleased by the comic book shop's new-found popularity. Raj tries to take the credit for Penny's astronomical discovery. (S11 Ep21) [AD,S]
The Monetary Insufficiency: Sheldon goes to Las Vegas to try to win money for science. Penny and Bernadette take Amy shopping for a wedding dress. (S11 Ep22) [AD,S]
The Hook-Up Reverberation: Raj's honesty about his past comes back to haunt him when his girlfriend Emily gives Penny the cold shoulder. The guys consider an investment. (S8 Ep4) [AD,S]
The Focus Attenuation: The guys attempt to invent something of scientific importance but only come up with new and enjoyable ways to procrastinate. (S8 Ep5) [AD,S]
The Expedition Approximation: Sheldon and Raj try to find out if they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a tunnel. (S8 Ep6) [AD,S]
The Hook-Up Reverberation: Raj's honesty about his past comes back to haunt him when his girlfriend Emily gives Penny the cold shoulder. The guys consider an investment. (S8 Ep4) [AD,S]
The Focus Attenuation: The guys attempt to invent something of scientific importance but only come up with new and enjoyable ways to procrastinate. (S8 Ep5) [AD,S]
The Expedition Approximation: Sheldon and Raj try to find out if they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a tunnel. (S8 Ep6) [AD,S]
The Skywalker Incursion: When Leonard and Sheldon are invited to speak at Berkeley, they take a detour during the journey to try to meet one of their idols. (S8 Ep19) [AD,S]
The Fortification Implementation: When Sheldon and Amy build a blanket fort, they come to a major crossroads in their relationship. Howard meets his half-brother. (S8 Ep20) [AD,S]
The Communication Deterioration: Raj is asked to create a message for NASA to use if one of their missions finds alien life. Penny considers taking up acting again. (S8 Ep21) [AD,S]
The Skywalker Incursion: When Leonard and Sheldon are invited to speak at Berkeley, they take a detour during the journey to try to meet one of their idols. (S8 Ep19) [AD,S]
The Fortification Implementation: When Sheldon and Amy build a blanket fort, they come to a major crossroads in their relationship. Howard meets his half-brother. (S8 Ep20) [AD,S]
The Communication Deterioration: Raj is asked to create a message for NASA to use if one of their missions finds alien life. Penny considers taking up acting again. (S8 Ep21) [AD,S]
The Sibling Realignment: When Sheldon finds out that his mum won't come to his wedding unless he invites his brother Georgie, he and Leonard head to Texas. (S11 Ep23) [AD,S]
The Bow Tie Asymmetry: Everyone is focused on making sure that the arrangements for Amy and Sheldon's big day go according to plan - except the bride and groom. (S11 Ep24) [AD,S]
The Holiday Summation: After spending Christmas apart, the gang gather at Penny and Leonard's flat and hear about Sheldon and Amy's terrible trip to Texas. (S10 Ep12/24) [AD,S]
The Clean Room Infiltration: Amy hosts a Victorian Christmas Eve dinner, complete with party games. Raj, Leonard and Howard have pigeon problems. (S8 Ep11/24) [AD,S]
The Cooper Extraction: Sheldon has to go back to Texas when his sister goes into labour. While he's away, the gang gather at the flat to decorate the Christmas tree. (S7 Ep11/24) [AD,S]
The Santa Simulation: Sheldon unwillingly reveals painful memories of Christmas past when Leonard persuades him to join in with a seasonal game of Dungeons & Dragons. (S6 Ep11/24) [AD,S]
The Maternal Congruence: Leonard is horrified when his mother turns up unannounced for a Christmas visit, and then he finds out that Sheldon knew about her divorce before him. (S3 Ep11/23) [AD,S]
The Bath Item Gift Hypothesis: At Christmas, Leonard's hunky colleague starts dating Penny, while Sheldon's obsession with gift-giving etiquette torments everyone. (S2 Ep11/23) [AD,S]
The Stockholm Syndrome: Howard and Bernadette go on a trip without their children, Leonard and Penny try to keep a secret, and Raj makes a new friend. (S12 Ep24/24) [AD,S]
The Change Constant: Sheldon and Amy stay up late awaiting a phone call that could bring big news from the Nobel Committee: are their lives about to change? (S12 Ep23/24) [AD,S]
The Countdown Reflection: Bernadette decides that she wants to get married to Howard before his NASA space mission, but can they get organised in time? (S5 Ep24/24) [AD,S]
The Launch Acceleration: When NASA inform Howard that his space mission has been rescheduled to an earlier date, he tries to use the wedding as an excuse not to go. (S5 Ep23/24) [AD,S]
The Transporter Malfunction: Penny buys Leonard and Sheldon some Star Trek memorabilia, but she is irked when they refuse to remove the toys from their packaging. (S5 Ep20/24) [AD,S]
The Weekend Vortex: Amy is upset when Sheldon breaks his promise to attend her aunt's birthday party in order to join the guys for a Star Wars video game marathon instead. (S5 Ep19/24) [AD,S]
The Werewolf Transformation: Sheldon's well-organised world is turned upside down when he learns that the barber who has cut his hair for years is ill in hospital. (S5 Ep18/24) [AD,S]
The Rothman Disintegration: Sheldon and Kripke argue over who should get Professor Rothman's vacant corner office. Amy buys Penny some art to celebrate their friendship. (S5 Ep17/24) [AD,S]
The Vacation Solution: Sheldon helps Amy in her biology lab after he is forced to use up two weeks of holiday, but he is bored by the tasks that she gives him. (S5 Ep16/24) [AD,S]
The Friendship Contraction: After Sheldon keeps him awake all night, an irate Leonard decides he needs to break the roommate agreement, which formally ends their friendship. (S5 Ep15/24) [AD,S]
The Beta Test Initiation: Leonard and Penny put their relationship through a 'beta test' and report problems with each other as 'bugs'. Sheldon and Amy seek internet fame. (S5 Ep14/24) [AD,S]
The Recombination Hypothesis: In the 100th episode of the US sitcom, Leonard and Penny agree to give their relationship another chance, but they soon start to argue again. (S5 Ep13/24) [AD,S]
The Shiny Trinket Maneuver: When Sheldon is dismissive of Amy's career, Penny, Raj and Leonard teach him that sometimes it's a good idea to pretend to care about things. (S5 Ep12/24) [AD,S]
The Speckerman Recurrence: Leonard confronts the man who bullied him in high school, while Penny realises that she did her fair share of tormenting in the past. (S5 Ep11/24) [AD,S]
The Flaming Spittoon Acquisition: Stuart from the comic book shop invites Amy out on a date. Consumed by jealousy, Sheldon then asks her to be his girlfriend. (S5 Ep10/24) [AD,S]
The Ornithophobia Diffusion: Leonard and Penny attempt to spend time together as friends without anybody else around, while Sheldon faces his fear of birds. (S5 Ep9/24) [AD,S]
The Isolation Permutation: Amy is heartbroken when she finds out that Penny and Bernadette went on a shopping trip to buy bridesmaids' dresses without her. (S5 Ep8/24) [AD,S]
The Good Guy Fluctuation: Leonard doubts his feelings for Priya when he kisses a woman he meets in the comic book shop. The gang pull pranks on Sheldon to celebrate Halloween. (S5 Ep7/24) [AD,S]
The Rhinitis Revelation: Sheldon's mother Mary comes to town and soon becomes a firm favourite with his friends, much to Sheldon's annoyance. (S5 Ep6/24) [AD,S]
The Russian Rocket Reaction: Sheldon's old nemesis Wil Wheaton returns and invites everyone to a housewarming party. But Sheldon threatens to 'de-friend' Leonard if he attends. (S5 Ep5/24) [AD,S]
The Wiggly Finger Catalyst: Raj begins to get upset that he's the only one of the four guys not in a relationship, so Penny sets out to find him the perfect date. (S5 Ep4/24) [AD,S]
The Pulled Groin Extrapolation: Leonard goes to a colleague's wedding as Amy's date. Howard tries to convince Bernadette to live with his mum after they get married. (S5 Ep3/24) [AD,S]
The Infestation Hypothesis: Amy is stuck in the middle of a battle of wills between Penny and Sheldon. Leonard and Priya try to spice up their long-distance relationship. (S5 Ep2/24) [AD,S]
The Skank Reflex Analysis: Penny worries that she's screwed things up with her friends after her night with Raj. Sheldon takes command of the paintball team. (S5 Ep1/24) [AD,S]
The Roommate Transmogrification: Raj decides to move in with Sheldon after hearing Leonard and Priya engaging in a Star Trek bedroom fantasy. (S4 Ep24/24) [AD,S]
The Engagement Reaction: Howard finally tells his mother that he's engaged to Bernadette. Unfortunately, the news lands his mum in hospital. (S4 Ep23/24) [AD,S]
The Wildebeest Implementation: Raj attempts to overcome his anxiety about talking to women, while Penny uses Bernadette to spy on Leonard and his girlfriend. (S4 Ep22/24) [AD,S]
The Agreement Dissection: Priya uses her legal expertise to dissect the roommate agreement and put Sheldon in his place, and the girls take Sheldon dancing. (S4 Ep21/24) [AD,S]
The Herb Garden Germination: Sheldon and Amy experiment on their friends by spreading gossip, while Howard takes a big step in his relationship with Bernadette. (S4 Ep20/24) [AD,S]
The Zarnecki Incursion: When somebody hacks into Sheldon's online gaming account, he and his friends become determined to locate the culprit. (S4 Ep19/24) [AD,S]
The Prestidigitation Approximation: Leonard must choose between his new girlfriend Priya and his friendship with Penny. Howard drives Sheldon crazy with a magic trick. (S4 Ep18/24) [AD,S]
The Toast Derivation: Sheldon is surprised and disturbed to find out that it's really Leonard who is at the centre of their group of friends and not him. (S4 Ep17/24) [AD,S]
The Cohabitation Formulation: Howard is torn between taking things to the next level with Bernadette and pleasing his mother. Leonard rekindles his relationship with Priya. (S4 Ep16/24) [AD,S]
The Benefactor Factor: A wealthy benefactor at the university makes Leonard consider how far he's willing to go in the name of science. (S4 Ep15/24) [AD,S]
The Thespian Catalyst: Sheldon lectures at the university but worries that the students don't seem to like him. Raj fantasises about his best friend's girlfriend. (S4 Ep14/24) [AD,S]
The Justice League Recombination: The guys slowly warm to Zack and find an enjoyable way to bond with him when they enter a New Year's Eve fancy dress competition together. (S4 Ep11/24) [AD,S]
The Alien Parasite Hypothesis: Amy realises that she has romantic feelings for Zack. Raj and Howard compete to prove who would make the better superhero. (S4 Ep10/24) [AD,S]
The Boyfriend Complexity: When Penny's father visits, Leonard discovers that her parents still think that he and Penny are a couple, so he takes advantage of the situation. (S4 Ep9/24) [AD,S]
The 21-Second Excitation: The gang's plans to attend a film screening are scuppered by Sheldon's nemesis Wil Wheaton. Penny and Bernadette invite Amy to her first slumber party. (S4 Ep8/24) [AD,S]
The Apology Insufficiency: Leonard thinks his dating problems are due to a lack of confidence, and vows to be self-assured around attractive women. Howard is called by the FBI. (S4 Ep7/24) [AD,S]
The Irish Pub Formulation: A visit from Raj's sister Priya creates tension among the guys, especially when Leonard asks Sheldon to conceal his romantic past with her. (S4 Ep6/24) [AD,S]
The Desperation Emanation: Leonard realises he's the only one of the gang with no girlfriend. Sheldon wants to get rid of his when she hatches a plan for him to meet her mother. (S4 Ep5/24) [AD,S]