The Big Bang Theory (season 10)

The gang prepares for Leonard and Penny's second wedding ceremony. Sheldon and Leonard fear that Mary slept with Alfred the previous night, though they swear nothing happened. They do, however, plan to visit each other, irritating Beverly. Penny's family arrives. Her mother worries that her son's recent jail stint will cause Leonard's family to think of them as white trash. The ceremony goes well, with Leonard and Penny declaring their love for each other, Beverly and Alfred grateful they at least made Leonard together during their relationship, and Sheldon declaring his love for the couple. Howard is repeatedly contacted by Air Force Colonel Richard Williams, who scares both him and Raj. Howard eventually agrees to meet him, but the colonel refuses to give the reason for his interest.

Leonard and Howard worry the military might try to take over the guidance system project for weaponry, but Sheldon does not. They make him promise not to talk during the meeting with Colonel Williams. The Colonel is impressed with Howard as the main brain behind the project, making Sheldon squirm. The military wants a smaller version made, perhaps in four months. Sheldon, no longer able to contain himself, promises to have it in two. Though the others are angry about such a tight deadline, they all have fun with their new lab's retinal scanner. Meanwhile, the pharmaceutical company employees have found out Bernadette is pregnant, infuriating her as they might take her off the next big medical project. Penny admits she was the one who let this slip. Bernadette forgives her because she intends to threaten her boss with a lawsuit if she is taken off the project.

Sheldon, Leonard, and Howard are exhausted from trying to meet the Air Force's deadline. In a dream, The Flash convinces Sheldon to take an energy drink. After it wears off, Sheldon is convinced he is addicted, further annoying the other two. Sheldon breaks down and admits he cannot figure out the math and isn't as smart as he thought. The others comfort him. Facing Colonel Williams, they admit that they need at least two years, which is easily accepted, as the military is used to contractors not meeting deadlines. Amy takes Penny to a party thrown by Bert the geologist, but they discover that they are the only ones there. Bert shocks them by saying Amy is the most popular scientist at Caltech and falls in love with Penny. Raj tries to help Bernadette get the nursery ready, but she doesn't enjoy it. She admits her lack of excitement makes her fear she cannot be maternal. Raj calls his OB-GYN father, who tells Bernadette that, while she may not like babies in general, she can still love her own child.

After a plumbing problem makes Amy's apartment uninhabitable for five weeks, Leonard and Penny suggest Amy move into Leonard and Sheldon's apartment. After Amy proposes their cohabitation as an experiment, Sheldon agrees to move with her into Penny's apartment, thrilling Leonard and Penny. Amy's first night in Sheldon's bed is rough and she doesn't get much sleep due to Sheldon's tossing and turning. The next morning, they fight over scientific integrity, working themselves up until Amy suggests they head for Penny's apartment to make out. After an ultrasound, Howard and Bernadette are angry that Raj knows the sex of their baby when they had elected not to find out. They have a rough night debating whether to call Raj about it.

Amy and Sheldon storm into Leonard and Penny's apartment arguing about Sheldon requiring a bathroom schedule. To help him cool off, Penny takes Sheldon to an ice cream parlor, where he tries to hunt for more partners. Sheldon confesses he once walked in on his father with another woman, which is why he always knocks three times when entering a room now, and it makes him worry that he'll hurt Amy one day. Penny convinces him to give the relationship a chance. Leonard coaches Amy on how to live with Sheldon. Returning, Sheldon agrees to compromise, so he does away with the bathroom schedule and agrees to share a toothbrush holder, a big step for Sheldon. After a canceled weekend away, Howard and Bernadette find Raj and Stuart secretly coming into their house and using the hot tub. They listen in as Raj reveals he is now single, but finally kick them out when Stuart says he isn't wearing a bathing suit.

Sheldon throws a brunch to surprise Amy, who wanted to invite guests over; Stuart, Bert from the geology lab, and a Romanian neighbor from downstairs attend. Stuart is insulted when he learns that the brunch was a test run before they invited others over; Sheldon apologizes and they get drunk, complimenting each other and annoying Amy. Penny gets invited to a Van Nuys Comic-Con event to sign autographs since she starred in two Serial Apeist movies; she is humiliated by fans deriding her poor acting ability but loving her topless shower scene. Leonard ends up holding court describing how he married such an attractive woman. Howard finally feels the baby kick. He and Raj go shopping, buying a crib and a minivan, but Howard throws his back out and they drive to the ER.

Sheldon finds out via Bernadette and Howard that Amy's apartment was repaired two weeks ago and Amy lied about it to keep living with him. Sheldon forgives her and wants to keep living with her, but is torn about where he really belongs. He chooses to live with Amy. Meanwhile, Penny has been secretly moving Leonard's collectibles into storage. He confronts her, but he agrees she could decorate their bedroom to make her feel at home while his stuff goes into Sheldon's old room.

Amy uses skin cells from her and Sheldon to produce some primitive neurons through transdifferentiation. This inspires Sheldon to want to have a child with Amy, though she is not enthusiastic about his plan to have a child immediately. Sheldon launches a plan to seduce his girlfriend. Raj becomes attracted to Isabella, a cleaning woman at his lab, and fixes her dinner. She is insulted when she discovers that Raj told his friends that she was a fellow astronomer, but agrees to another date.

Sheldon learns that Bert has won a MacArthur Fellowship prize for his work on endolithic organisms, and has to deal with his professional jealousy. The rest of the group discuss their own internal jealousies. Professor Hawking calls Sheldon and explains that even he gets jealous. In order to make peace, Sheldon goes with Bert to a taping of The Ellen DeGeneres Show. Meanwhile, Howard builds a remote controlled miniature Stephen Hawking, and while everyone (except Kripke) thinks it is offensive, Hawking actually likes the idea.

After Sheldon and Amy take the ugly portrait of Penny and Amy to Leonard and Penny's apartment, the guys start to divide up their belongings. When Sheldon tries to take everything, a dispute over the official apartment flag starts a war between Sheldon and Leonard. Sheldon rents out his old room to an old guy named Theodore (Christopher Lloyd) who helps them to realize that Sheldon moving out is affecting both of them deeply, leading to Sheldon allowing Leonard to keep the flag. Stuart brings Howard and Bernadette a gift and ends up moving back in since he was evicted from his apartment. Stuart plans to help them out to justify his moving in, starting a war with Raj who claims the right to help them. Finally, Bernadette goes into labor and everyone heads to the hospital for the arrival of their baby.