Leonard tells Penny about how he met Sheldon for the first time…and what happened to the elevator.

Sheldon’s search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

A robbery of their apartment sees Leonard and Sheldon call on their friends to devise a security system.

Sheldon attempts to help Penny understand Leonard’s work, and Wolowitz becomes jealous when Leonard starts hanging out with his new girlfriend.