The show starts by being centred on two male Caltech scientists who share an apartment in Pasadena, California. They are in their twenties and are both single for the first two seasons. One is an experimental physicist from New Jersey (Leonard Hofstadter). The other is a theoretical physicist from Texas (Sheldon Cooper). Sheldon has Asperger syndrome and obsessive-compulsive personality disorder and has a very low sex drive. They live across the hall from an attractive, bottle-blonde waitress from Nebraska (Penny). She is single and lives on her own for most of the show's run. She tried to become an actress, but only got a role in a television advertisement and a role in a B-movie called Serial Apeist as well as its sequel.