The guys become sleuths to find out who hacked Sheldon's online-game account

Leonard is forced to choose between Penny and his new girlfriend, Priya; Howard's magic trick drives Sheldon crazy.

Sheldon is upset when he realizes Leonard is the center of their group of friends.

Wolowitz considers taking things with Bernadette to the next level; Leonard and Raj's sister rekindle their relationship.

A wealthy donor makes Leonard question what he is willing to do for science.

Sheldon takes acting lessons from Penny in hope of becoming a better teacher; Koothrappali fantasizes about his friend's girlfriend.

Bernadette runs into her ex-boyfriend (Rick Fox) while attending a science event with Wolowitz.

Leonard realizes he's the only one without a girlfriend, while Sheldon wants to get rid of his.

An embarrassing secret of Wolowitz's is revealed; Raj and Sheldon get into a war at work.

When Sheldon searches for an alternative to human companionship, the guys become concerned.

Realizing he will not live long enough to download his consciousness into a robot body, Sheldon tries to extend his life span.

Penny tags along on Sheldon's first date; Wolowitz finds a new use for a robotic arm.