Two physicists learn how little they know about life when a beautiful woman comes into their lives. When Leonard and Sheldon meet Penny, Leonard is immediately interested in her, but Sheldon feels his friend is chasing a dream he'll never catch.

Sheldon and Leonard go to Penny's apartment to drop off a package, but Sheldon can't believe how messy her apartment is.

Leonard is depressed when he discovers that Penny is dating someone. As a result, and encouraged by his friends and fellow scientists, Leonard actually summons up the courage to ask a woman out on a date.

Getting fired forces Sheldon to explore life outside physics, leaving Leonard to take drastic action to snap his friend out of his reverie.

Leonard fears that he's wasting his time on Penny, so he ends up making a connection with Leslie. Meanwhile, Sheldon frets over a change to his hamburger routine.

Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz and Koothrappali through a new test of their social skills.