The network says Duff will play "Morgan Jefferies, a beautiful woman of mystery who may be involved in the death of a man who fell victim - literally - to a freak accident."
Whatever the mystery is, we're sure it will give Jennifer Love Hewitt's Melinda the chance to do plenty of whispering with ghosts.
Duff's episode will air on Friday, April 10.
While the CBS press release refers to Duff merely as a "pop singer," her TV acting credits include a starring role on the long-running "Lizzie McGuire" and a guest appearance on CBS' "Joan of Arcadia." She also recently inked a talent development deal with NBC.
On the big screen, Duff was last seen in the satire "War, Inc.," while she just signed on to star in the film "The Story of Bonnie and Clyde."
CBS has been busy casting familiar musical faces in its dramas. Taylor Swift will co-star in an upcoming episode of "CSI: Crime Scene Investigation," while Pete Wentz and Ashlee Simpson-Wentz will guest on the March 18 episode of "CSI: NY."