With Wolowitz AWOL with one of her friends, Penny's recruited to fill in for him on the guys' Halo team.
Penny hosts a Halloween party, putting Leonard, Sheldon, Wolowitz, and Koothrappali through a new test of their social skills.
Fearing he's wasting his time on Penny, Leonard ends up making a connection with Leslie. Meanwhile, Sheldon frets over a change to his hamburger routine
Sheldon's getting fired forces him to explore what life has to offer outside physics, leaving Leonard to take drastic action to snap his friend out of his funk.
Leonard asks a woman out after he finds out that Penny is seeing someone.
Leonard volunteers to sign for a package in an attempt to make a good impression on Penny, but when he enlists Sheldon for help, his attempt at chivalry goes terribly awry.
Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins showing them that as much as they know about science, they know little about actual living.