This just in...

ET has confirmed that new mom Nicole Richie is heading back to work when she guest stars on an episode of "Chuck," NBC's hour-long comedy series about spies, which will air this fall.

"Nicole auditioned for the part and was very funny," says executive producer Josh Schwartz. "This role is a great opportunity for her to show off her comedic skills and be diabolically evil and kick some butt. It's going to be really fun."

Nicole will play a former mean girl schoolmate of Sarah's (series star Yvonne Strahovski), who tortured the special agent back during their high school days. The two have a close encounter when they come face to face at their 10-year high school reunion, where Sarah is on a mission.