"Chuck" will return on September 20 with an episode featuring Olivia Munn as the new Nerd Herd member. However, Munn's character is more than meets the eye. She is one of the CIA agents who go undercover with code name "Greta".

The first look of Munn as Greta has been released, revealing as well that Buy More is back to business after being destroyed at the end of last season. According to some reports, the store is now directly run by CIA and Greta who is deemed master of disguise, will be in charge.

To succeed Munn as Greta are Stacy Keibler and Isaiah Mustafa. "Greta can be a guy or a girl, which is brilliant," Zachary Levi said. "The Buy More has now been taken over by the CIA and it's a fully functioning operation by the government, so there are these constant agents that are in the store. First it was Olivia Munn, who looked hot in her little Nerd Hereder outfit, and [next was] Isaiah [Mustafa], who was a hoot to work with."

Beside Munn, the season opener titled "Chuck vs. the Anniversary" would also present Dolph Lundgren who will "try and break" Chuck.