On The Big Bang Theory Season 12 Episode 24, the gang travel to Sweden to see Amy and Sheldon receive the Nobel Prize but pressures threaten to destroy their friendship.
Two months later, Amy and Sheldon have bought plane tickets for all their friends to travel to Sweden to witness the Nobel Prize ceremony. Leonard and Penny are secretly pregnant, accidentally conceiving the night Penny went out drinking with Sheldon.
Howard and Bernadette are anxious about leaving their kids with Stuart and Denise. Raj cautiously instructs Bert on how to take care of Cinnamon.
On the plane, Raj suspects the woman sleeping in the seat next to him is Sarah Michelle Gellar.
Meanwhile, Penny repeatedly rushes to the bathroom. Sheldon suspects that she is ill and becomes fixated on the idea that she may infect him and Amy before the ceremony, ruining the best day of his life. Leonard and Penny share their news with him and he's relieved that it's not contagious, a reaction which irritates Leonard.
In Sweden, Howard and Bernadette discover that Stuart and Denise aren't the best childminders and want to return home. Despite apologizing to Leonard at Amy's insistence, Sheldon reacts badly when Howard suggests that he and Bernadette head home. Everyone plans on going and Amy tells Sheldon that it's his fault even though he didn't do it on purpose.
Leonard and Penny change their minds and Bernadette's parents take over for Stuart and Denise so they stay too. Amy and Sheldon receive their award and Sheldon discards his prepared speech and delivers a heartfelt tribute to his friends instead.
On The Big Bang Theory Season 12 Episode 24, Sheldon and Amy stick together, and Koothrappali makes a new friend as the gang travels together into the future.