First look at images from the Season 4 premiere of Chuck. "Chuck" premieres Monday, Sept. 20 on NBC.
Chuck Bartowski (Zachary Levi) and the newest member of the Nerd Herd, guest star Olivia Munn.
Munn is playing a CIA officer code-named "Greta" -- a role that will change throughout the season and provide the opportunity for more guest casting. Munn's character will try to blend in at the Buy More, which also means she'll encounter Morgan