Two physicists, Sheldon and Leonard, pay a visit to a high-IQ sperm bank. Sheldon worries that the woman who gets his sperm might be disappointed with the outcome, citing his sister - who is a hostess at Fudrucker's - as an example. The guys leave without making their charitable contributions.
When they get back home, they notice that a new neighbor has moved in across the hall; it's a beautiful, young blonde woman. Leonard decides to take the initiative to be a good neighbor and invites her over for lunch. After some nerd-fueled rambling from Leonard and Sheldon, they learn that their neighbor, Penny, moved to LA from Nebraska; she is a waitress at The Cheesecake Factory, wants to be an actress, and recently broke up with her boyfriend, who turned out to be a jerk. She becomes very upset, and complains that her shower doesn't even work, so Leonard offers to let her use theirs.
While Penny showers, Sheldon tells Leonard that she is never going to sleep with him. Their friends, Raj and Howard, show up unexpectedly with a Stephen Hawking lecture. As soon as he gets an eyeful of Penny, Howard turns on the charm. Penny doesn't seem too interested. She asks Leonard and Sheldon to please retrieve her TV from her boyfriend, and Leonard agrees to do so, leaving Penny with Raj and Howard. While Howard tries his best, Penny discovers that Raj cannot talk to women - literally.
Meanwhile, Sheldon and Leonard attempt to rescue Penny's TV, but her hulking ex instead relieves them of their pants. They arrive back at the apartment and Penny sweetly offers to buy all of them dinner for their trouble. Chagrined, Sheldon realizes that Leonard is not done trying to woo the girl next door.