Kristen Stewart is headed for the slammer!

We hear the 19-year-old actress and her Twilight co-star Nikki Reed, 21, have been cast as inmates in an upcoming dark comedy directed by Kristen’s mother. Jules Mann-Stewart is stepping behind the camera for her directorial debut in K-11, a knee-slapping story about a unit of the Los Angeles County Jail that frequently houses high-profile prisoners.