1 Series, 4 Episodes
Leonard jumps through hoops to secure the perfect wedding venue for Sheldon and Amy. Howard and Bernadette must decide which of them should stay at home with the kids and who should return to work.
When Bernadette can't go into labour, her friends try different tactics to get things started. Howard confronts Bernadette after Amy accidentally reveals that she has already chosen their son's name.
Sheldon asks Wil Wheaton if he can appear on the new Professor Proton show, but Wil invites Amy instead. Penny gets angry when she thinks the female protagonist in Leonard's novel is based on her.
Raj gets into a domestic drama with his new date and her estranged husband. Sheldon rents his old room back to have a quiet place to work but drives Leonard to distraction by being a model tenant.
Sheldon needs some 'alone time' to work, so Amy and Leonard bond during a series of science experiments. Bert replaces Howard in his band, while Penny gives Sheldon unexpected scientific inspiration.
Sheldon and Amy secretly test their friends to see who is the most qualified to act as best man and maid of honour at their wedding. And Penny realises her true feelings about her friendship with Amy.
Sheldon and Howard plan birthday celebrations for Amy and Halley, respectively. Leonard receives a Christmas letter from his brother that makes him feel anxious about his own lack of accomplishments.
Sheldon and Amy try to eliminate stress from the planning of their wedding by applying mathematics to the process. Raj falls out with Howard after realising his best friend is hurting his confidence.
Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable investment. Meanwhile, a seven-year-old video reveals a secret about Leonard and Penny's relationship.
Leonard and Howard are furious when they learn that Sheldon went to work with the military behind their backs. Bernadette suspects that Ruchi is trying to steal her job and asks Raj to investigate.
Sheldon and Bert collaborate on some research, although Sheldon's embarrassed to be associated with the study of geology. Penny and Bernadette coach Raj on how to navigate his relationship with Ruchi.
Sheldon goes head-to-head with Wil Wheaton as they compete for the role of the new Professor Proton when the scientist's old TV show gets a reboot. Penny looks after Halley for Howard and Bernadette.
Sheldon and Raj ask Bernadette for advice about their jealousy when Amy and Howard collaborate on a new project. Penny and Leonard learn new ways to manage Sheldon's behaviour from an unlikely source.
Howard and Sheldon bond when they drive into the desert to shoot off a model rocket. And when Leonard's mother Beverly finds a new best friend in Penny, it rubs Leonard up the wrong way.
As Sheldon stresses out about picking a wedding date, Amy tries to convince him that he has a more laid-back side. Raj and Stuart compete to win the heart of Bernadette's new colleague Ruchi.
Leonard angers the university - and the entire physics community - when he gives an embarrassing interview. Amy and Bernadette bond over having to hide their success from Sheldon and Howard.
Amy must decide whether or not to marry Sheldon and gives him an answer to his proposal. Meanwhile, Howard and Bernadette struggle with some unexpected news.