Banished to an insane asylum in post-Revolutionary France, the Marquis de Sade (Geoffrey Rush) begins to write as his protest against the political forces who placed him there. The priest who runs the asylum (Joaquin Phoenix) feels sympathy for the Marquis, and allows the Marquis freedom to write and perform theater that is sympathetic towards the former monarchy and a challenge to the current authority The prison warden (Michael Caine) is outraged and takes away the writing quills of the Marquis, but cannot stop the Marquis from writing, as the Marquis resorts to anything to be able to write, even going so far as using wine and his blood to pen his works. When those options are removed, the Marquis seduces a beautiful laundry girl, Madeline (Kate Winslett) to help smuggle out his manuscripts. When Madeline is killed by an inmate, the Marquis' and his stories are blamed for inciting the passions of the inmates resulting in his final banishment into true insanity.