Rush is the Marquis de Sade, locked up in an asylum, but assisted by a chambermaid (Winslet) in writing his stories, until hard-core doctor Caine brings a crackdown.
This plays as an interesting counter to the classic "have sex and die" horror movie - of the three characters who don't get their ends away, the final score is two dead, one loony. However, though I agree with the stance against religion and in favour of moral freedom, it comes over as very short on intellectual rigour. Instead, while appropriately moist and sweaty,
the movie comes across almost as a hagiography for the Marquis; the reasons why he's locked up are glossed over, and he comes across as an affable dirty old man, rather than a talentless psychopath (ever tried to read any de Sade? It's dire). It would have been better to have had someone challenge de Sade's views, and go toe-to-toe with him intellectually. But Caine is the only person who doesn't seem in love with him, and he's too busy screwing his under-age wife to take the moral high ground. There's a lot of juicily grand guignol revenge here, and this, together with Rush getting his teeth firmly into his role, is the main joy to be found here.