Penny Can't Find Her Fire for Life on 'Big Bang'

Penny Can't Find Her Fire for Life on 'Big Bang'

"Penny" is usually a peppy character on The Big Bang Theory, but on tonight's episode she can't seem to find her passion for life. ET has your sneak peek.

On the episode, entitled "The Closure Alternative," Penny (Kaley Cuoco) is disillusioned when she is uninterested in an episode one of her boyfriend's favorite television shows, which she has just watched with "Bernadette" (Melissa Rauch).

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Her disinterest forces her to reflect on the general lack of passion in her life.

"[Leonard] is passionate about so many different things," she gripes to Bernadette. "I just don't get that way. ... I wish I had some of that fire in my life. I want to care about things and get excited like you guys."

Although she wants to recapture her fervor for life, Penny isn't too keen on taking the time and energy to discover something that she can get interested in and passionate about.

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Penny isn't the only one in the gang who is disenchanted in the episode, as "Sheldon" (Jim Parsons) feels lost in life as well when one of his favorite TV shows gets canceled prematurely. His girlfriend, "Amy" (Mayim Bialik), tries to help him overcome his need to feel closure, which is making him grumpy.

Watch the clips above for a sneak peek, and check out the full episode of The Big Bang Theory tonight at 8 p.m. on CBS.