Leonard angers the University and the Physics Community when he gives an embarrassing radio interview. Bernadette and Amy compare their successes at work.
Amy and Howard work in the lab together causing Sheldon, Bernadette and Raj to feel jealous and lonely. Penny starts using a parenting book to control Sheldon's behavior.
Sheldon and Wil Wheaton both go head-to-head for the role of the new Professor Proton, Meanwhile Penny takes care of Halley when Bernadette and Howard are on bed rest.
When Bert asks Sheldon to collaborate on a project with him, Sheldon becomes worried about others finding out because he thinks geology is beneath him. Raj seeks advice after reconnecting with Ruchi.
Howard and Leonard become upset after they discover that Sheldon has been working with the military without telling them; Bernadette asks Raj to investigate her suspicions that Ruchi is attempting to take her job away from her.
Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process. Raj and Howard come to blows when Raj begins to feel like Howard hurts his confidence.
Raj and Howard's feud continues as the gang plan Halley's first birthday party. Sheldon's surprise for Amy's birthday goes awry when they get food poisoning.
Sheldon and Amy pick their best-man and maid of honor by experimenting on the gang. Meanwhile, Leonard's self-confidence is still badly damaged after reading his brother's Christmas letter.
Sheldon kicks Amy out of the apartment to work solo, and she and Leonard end up bonding during a series of science experiments; Howard is replaced by Bert in Footprints on the Moon.
When Bernadette won't go into labor, the gang try different tactics to get things started. Also, Wolowitz confronts Bernadette after Amy accidentally reveals she's already chosen their son's name.
Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy. Also, Bernadette and Wolowitz have a hard time deciding who should stay at home with the kids and who should go back to work.
Leonard, Howard and Raj try to meet Bill Gates, who's meeting with Penny to merge their companies; Sheldon thinks he's the victim of an April Fool's prank.
Sheldon's comic book store experience changes when writer Neil Gaiman puts Stuart's store on the map; friendships are threatened when Koothrappali takes credit for Penny's astronomical discovery.
Sheldon goes to Vegas to win money for science. Also, Penny and Bernadette take Amy wedding dress shopping, but her terrible choice entangles them in a web of lies.
When Amy's parents and Sheldon's family arrive, everybody is focused to make sure all wedding arrangements go according to plan - everyone except the bride and groom.
