On a new episode of NBC's returning drama Chuck (Mondays, 8-9 p.m. ET), Special Agent Sarah Walker (series star Yvonne Strahovski, Gone) gets a bad blast from the past when she comes face to face with her high school nemesis -- played by guest star Nicole Richie (The Simple Life) -- for broadcast this fall.

Richie will guest-star in the episode as the snarky and spiteful girl who tortured Sarah in school -- and now Sarah must face her fears when she is forced to attend her 10-year high school reunion for a mission with Chuck (series star Zachary Levi, Less Than Perfect) as her date.

"Nicole auditioned for the part and was very funny," said 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."

Richie recently was featured in cover stories for People magazine and Harper's Bazaar. Touted as a style icon, her fashion statements are regularly featured online, in print and on entertainment news shows. In addition to The Simple Life, on which she co-starred with Paris Hilton, Richie has guest starred on shows such as 8 Simple Rules... for Dating My Teenage Daughter and American Dreams. Richie is also launching a jewelry line, House of Harlow 1960, in the upcoming fall.

Chuck is a high-concept action comedy that follows Chuck Bartowski (Levi), a regular twentysomething whose life is thrown into disarray after his friend, a CIA agent, sends him an e-mail which results in the world's secrets becoming embedded in his mind. Chuck is just an ordinary guy who spends his days solving problems at an electronics store with a band of nerdy cohorts and longing to find a woman who can appreciate him. He never asked to become the government's most powerful weapon, but suddenly the fate of the country lies in his unlikely hands. Agents Sarah Walker (Strahovski) and John Casey (series star Adam Baldwin, Serenity) are assigned to protect him.

From College Hill Pictures, Wonderland Sound and Vision in association with Warner Bros. Television, Chuck was created by Josh Schwartz & Chris Fedak and is executive produced by Schwartz and McG.