Amy and Sheldon are working on an experiment to transform skin cells into brain cells, and Sheldon becomes very excited as they test their "brain in a bowl."

Meanwhile, Raj meets a janitor named Isabella while he's at work late one night, and she notices his bad eating habits. He develops a crush on her and starts eating a little bitter. When he orders broccoli for dinner, his friends notice and immediately realize he's interested in someone. They ask about her, and Raj lies about her profession.

Because their experiment has great results, Sheldon suddenly decides that he and Amy should have a baby. He tries to seduce her, but she's very annoyed with his idea and says she isn't ready for a baby.

Raj sees Isabella again at work and helps her clean bathrooms. Finally, he asks if he can take her to dinner, but she refuses because she says she's too busy to date.

Raj sets up dinner for Isabelle during work and convinces her to eat with him when Howard interrupts. He thinks she's an astronomer and Isabelle realizes Raj lied to his friends and is embarrassed by her profession.

He convinces her to let him make it up to her and take her to dinner that weekend.