The episode opens with a discussion about Howard's mother's health. Howard informs Leonard that because of his mother's behaviour two nurses have already left. When Raj enters Apartment A4, Leonard and Penny break the news that they are engaged. Everyone is euphoric hearing the news. Raj is a little disappointed because he thought he having sex with Emily would be the big news. It is the big news, as the cheering gang desert Leonard and Penny and surround Raj. Leonard and Penny getting engaged is regular news, and the engaged couple also agree.
Leonard comes to know that Sheldon has already informed his mother about the engagement. Also, Leonard's mother tells him that it is because of Sheldon, who put in a good word for Penny, that she is okay with Leonard and Penny's engagement. Penny, too, informs her family about the engagement and assures them that she is not pregnant. The wedding, however, is not happening soon, as Penny's brother is likely to come out of prison in 12 or 18 months.
An unemployed Penny agrees to the job of taking care of Howard's mother, as Bernadette offers to pay a huge amount. However, Penny, too, does not last long.
Meanwhile, Sheldon is frustrated as Caltech is not allowing him to change from string theory to inflationary cosmology. This is just the beginning of his trouble. Leonard tells him that he and Penny are planning to live together, without Sheldon. Leonard suggests to Sheldon that he can live across the hall. Sheldon finds Leonard's suggestion preposterous, and cannot believe that Leonard is choosing his future bride over him.
Sheldon gets more frustrated when Amy suggests that they can start living, together. And, when he finds Stuart's comic store destroyed by fire, Sheldon has had enough of dealing with all the changes. A worried Leonard accesses his phone records to find that Sheldon is at the railway station.
Penny and Leonard go to meet him. Sheldon has decided to move out to find himself, as he is unable to cope-up with all the changes that are happening around him. Penny tells Leonard that it will be good for Sheldon if he goes away. Afterwards, Amy hits Leonard with a cushion after Sheldon calls up to tell that he is doing fine.
Stuart gets hired to take care of Howard's mother. Howard and Bernadette can finally go to their home, as Stuart and Howard's mother have hit it off real well.