The script requires the sultry-voiced starlet to perform what she describes as a "long, lingering French kiss" with a woman.
The film also stars 47-year-old actress Caroline Quentin, best known for her roles in Men Behaving Badly and Jonathan Creek. Stone, who has sold over 10 million albums worldwide, said of the film: "There are things that are going to really push the boundaries - and that excites me."
The singer, who hails from Devon, can currently be seen on screens in a seductive reworking of the Cadbury's Flake television adverts.
