The new promo for Season 8 of CBS's The Big Bang Theory is centered around Sheldon's (Jim Parsons) sudden disappearance.

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Sheldon was getting ready to hop on a train at the end of Season 7 after learning that he and Leonard (Johnny Galecki) might be living in separate apartments after the latter got engaged to Penny (Kaley Cuoco-Sweeting). As seen in the new promo, Sheldon actually did get on the train and Amy (Mayim Bialik) is very upset about it.

"How could you let him go?!" Amy yells while beating up Leonard with a pillow.

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As seen very quickly into the trailer, though, Sheldon does indeed come back.

"I'm ready to deal with any changes that come my way," he proclaims as he enters his apartment.

At this point, Penny, who is sporting a new pixie haircut, sees him and says, "Look who's back?"

Sheldon is taken aback, responding, "Your hair is different. I can't take this, I'm out."

Penny's new haircut is a reflection of Cuoco-Sweeting's decision to cut her hair very short over the summer.

The series is gearing up for its eighth season and switching over to Mondays at 8 p.m. for a few months due to Thursday Night Football. The popular sitcom will return to its regular Thursdays at 8 p.m. during the week of Halloween.

The Big Bang Theory is set to premiere Monday, Sept. 22 at 8 p.m. ET/PT on CBS.

Watch the promo for the new season of The Big Bang Thoery here:

Tags: the big bang theory television CBS