When Leonard and Sheldon encounter a young woman crying on the curb, Leonard invites her to dinner. She is abrasive, sexy, hard, and sarcastic, but she softens a little when she discovers that the guys aren't trying to get something from her.

When they're invited to present at a physics conference, Sheldon's reluctance to share the credit leads to a tiff between him and Leonard, and Penny's intervention only exacerbates the situation.

Leonard and Sheldon compete for the attention of a famous female physicist.

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

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

An embarrassing secret of Wolowitz's comes to light, while Sheldon and Raj have a small war at work.

Sheldon's answers during an FBI interview put Wolowitz's security clearance in jeopardy.

Amy finds she has sexual feelings for Penny's ex, while Koothrappali and Wolowitz try to prove who would be the better superhero.

Bernadette runs into her ex-boyfriend while attending a science event with Wolowitz.

As Wolowitz contemplates taking things with Bernadette to the next level, Leonard rekindles his relationship with Raj's sister.

Sheldon's online-game account is hacked by Todd Zarnecki, who then proceeds to steal all his items prompting the guys to go on a quest to retrieve them. Penny, Bernadette and Amy discuss how Penny groomed Leonard to be willing to try various things and more adventurous boyfriend... for some other woman — Priya.

Raj attempts to cure his social anxiety disorder while Penny uses Bernadette to spy on Leonard and his girlfriend.