The Stockholm Syndrome is the twenty-fourth episode and season finale of Season 12, and more importantly, the series finale, of The Big Bang Theory, airing immediately after the penultimate episode, The Change Constant.
The gang goes to Stockholm, Sweden so Sheldon and Amy can win their Nobel Prize, Howard and Bernadette leave their kids behind, and Penny reveals that she’s pregnant.
Taking place two months after the previous episode, Sheldon and Leonard have finished putting Sheldon’s DNA model back together, which took almost six days but was rather enjoyable for Leonard. Sheldon constructed the genetic code for an advanced race of human beings. Penny and Amy arrive with the dresses for the Nobel Prize ceremony; Amy’s dress had to be let in, and Penny’s had to be let out. Sheldon and Amy go to their apartment so Amy can show him her dress, and Sheldon can practice his speech. After they leave, Penny reveals that she’s pregnant, which happened when she and Sheldon went for a drink.
At the Wolowitz house, Bernadette tells Michael that she and Howard are going to be gone for a few days. Halley has become a big girl having just used the potty. They have no qualms about leaving their kids with Stuart and Denise, and feel good to finally feel good to get some time to themselves again. Meanwhile, Raj leaves Bert to look after Cinnamon, hoping that he can attract some girls with her; Bert then makes a joke that he’ll get another dog just like her if she dies.
Amy is trying on her dress, while Sheldon is practicing his speech to get through it within 90 minutes. Amy proposes that he leave out his childhood, and all the people he thought would never get a Nobel Prize.
As they prepare to head to the airport, Sheldon and Amy tell everyone that they are ambassadors for them and to be on their best behavior, and give them advice on how to interact with the Swedish people. Sheldon also reminds Penny to go easy on alcohol on the flight, though Penny says that she’s not drinking; she doesn’t drink on flights. They try to go down in the newly repaired elevator with their luggage, but it becomes clear there’s no way they can all fit in the elevator with their luggage, so they end up going down the stairs while their luggage goes down in the elevator.
While on the plane, Bernadette is watching Jack Reacher movies, while Howard is feeling uneasy about Michael and Halley; Raj is sitting with Sarah Michelle Gellar from Buffy The Vampire Slayer. Meanwhile, Sheldon is concerned because Penny has gone to the bathroom five times in the past two hours. Amy makes the assumption that Penny is just airsick. When Penny comes out of the lavatory and immediately goes back in, Sheldon goes over to Leonard and expresses his concerns. Penny returns and tells Sheldon he has nothing to worry about, she’s just pregnant. Relieved, Sheldon tells Amy the good news. Leonard is disgusted that Sheldon isn’t a little more happy for Penny.
Amy is furious that Penny kept her pregnancy a secret. Bernadette comes over and Amy tells her about Penny’s pregnancy; for a second, Bernadette is thrilled before she, too, gets angry that she wasn’t told about it. Penny explains that it just happened when she and Sheldon went out for drinks.
Later, at the hotel, Bernadette talks with Stuart on Skype to make sure everything’s okay. Stuart tells her that Halley lost a tooth while rolling down the stairs, and Neil has a fever. Penny is helping herself to pickled herring, while Leonard is still very disappointed that Sheldon wasn’t a little more happy for him and Penny. Sheldon comes over to apologize to them and say congratulations. Howard arrives to say that he and Bernadette are thinking about going home because they’re worried about the kids, and when Sheldon tells him to keep it together, he decides he’s definitely going home. Fed up with Sheldon’s behavior, Leonard and Penny are leaving as well.
As he and Amy are getting ready for the ceremony, Sheldon expresses his disgust that their friends are choosing to leave them on their big day. Amy promptly explains they’re leaving because he unintentionally offended them as he always does, and they only put up with it because they’re his friends, adding that it’s true for her as well now and then.
Penny is sick from eating all that food. Even though she and Leonard are mad at Sheldon, they still want to be there to support him and Amy because they care about him. Leonard states that Sheldon has been their practice kid, in a sense. They then get a call from Howard, who tells them that they decided to stay; Bernadette’s parents are filling in for Stuart and Denise, and Mike accidentally broke one of Stuart’s ribs while hugging him.
At the ceremony, Sheldon and Amy are awarded their medals as the gang looks on; Raj brought Sarah Michelle Gellar as his guest. Amy gives a shoutout to young girls around the world, saying that winning a Nobel Prize is a great honor and that anyone interested in science should go for it, because it is the best job of all. Sheldon puts his long self-centered speech aside, and instead says that if it weren’t for his family and friends, he would never have reached his lifelong dream of winning a Nobel Prize. He always foolishly believed that his accomplishments were his doing. He always had support from his wife and friends; he then acknowledges Raj, Howard, Bernadette, Penny, and Leonard. Calling Penny and Leonard his dearest friends in the world, he recalls the day they first met, and that Leonard said they would one day have beautiful and smart kids. Penny is very touched by this, as she had yet to tell her parents. He then apologizes for being such a bad friend in all the time that they have known him, and says that he loves all of them in his own way, and Amy, too. Thanking all of them, he and Amy are met with applause.
Back in Apartment 4A, Bernadette, Howard, Leonard, Penny, Sheldon, Amy, and Raj are all having takeout food, talking and laughing, as an acoustic version of the show’s theme song plays in the background.
- Johnny Galecki as Leonard Hofstadter
- Jim Parsons as Sheldon Cooper
- Kaley Cuoco as Penny Hofstadter
- Mayim Bialik as Amy Farrah Fowler
- Simon Helberg as Howard Wolowitz
- Melissa Rauch as Bernadette Rostenkowski-Wolowitz
- Kunal Nayyar as Raj Koothrappali