VIDEO: Sneak Peek - Tonight's Episode of CBS's BIG BANG THEORY

On tonight's episode of CBS's THE BIG BANG THEORY, Sheldon tries to relax after he is forced to take a vacation. Meanwhile, Leonard struggles to be supportive of Penny after she quits her job, and Bernadette seeks Stuart's help in replacing one of Howard's comic books.

The episode airs tonight, Thursday, Jan. 9 (8:00 - 8:31 PM, ET/PT) on the CBS Television Network. Josh Peck guest stars as Jesse, the owner of a rival comic book store. Get a first look below!

Leonard and Sheldon are brilliant physicists - geniuses in the laboratory, but socially challenged everywhere else. Enter beautiful, street-smart neighbor, Penny, who aims to teach them a thing or two about life. Despite their on-again, off-again relationship in the past, Leonard believes he's found true love with Penny.

Even Sheldon has found a female companion, entering into a "Relationship Agreement" with neurobiologist Amy Farrah Fowler. In their free time, Leonard and Sheldon continue to enjoy frequent trips to the comic book store and fantasy role-playing games with their ever-expanding universe of friends, including fellow scientists Koothrappali, Wolowitz and Wolowitz's adorable microbiologist wife, Bernadette.