Is there any point in a prison movie if no-one tries to escape?  Probably not; which is why the climax of Steve Buscemi’s Animal Factory has a rookie prisoner making a bid for freedom in the back of a garbage truck.

This action gives the movie some semblance of a plot but narrative drive is not really its purpose. It works instead as a kind of dramatised documentary to expose what  life in US  prisons is really like. It is not a pretty sight.

The authentic quality comes from the fact that it is based on ex-con Edward Bunker’s real-life experiences behind bars. It is set in San Quentin and effectively lays to rest any woolly liberal notion that rehabilitation figures anywhere on the agenda.

Bunker somehow managed to leave his criminal past behind him and re-build a life as an actor and writer; he became Mr Blue in Tarantino’s Reservoir Dogs. He is surely an exception as it’s hard to see how most people would be able to live normally after enduring a punishing prison regime in which buggery and thuggery are the norm.

Edward Furlong plays Ron Decker who is inside awaiting trial on the relatively minor charge of drug possession. By choosing him as the focus, the film seems to make the point that if you weren’t fucked up when you enter the institution you sure as hell will be after  you’ve served your time. The title I therefore take to be a reference to the process whereby human beings are processed by the system to end up existing like animals.

William Dafoe is the shaven-headed veteran Earl Copen who takes a shining to Decker and,curiously, doesn’t appear to have any ulterior motives. Why he acts as he does is never entirely clear – he hardly strikes you as the type of guy to do a good deed out of the kindness of his heart.

Other inmates have a less benevolent attitude to this fresh meat and so Decker has to be constantly on his guard and stand his ground or die trying. Dafoe ,in contrast, is savvy enough to charm the prison guards yet has the constant appearance of a human bomb primed and ready to explode at any moment.

Other reasons to see it are to gawp at Mickey Rourke , all but unrecognisable as the muscle-bound transvestite Jan the Actress and enjoy the appropriately spiky soundtrack by John Lurie. You should also watch out for a cameo role by Antony Hegarty as a prison performer  who looks as nervous and vulnerable as I’m sure I would be if I had to spend more than five minutes inside.

Copen/Dafoe’s own bid for freedom is foiled and the movie ends with him philosophically quoting from John Milton’s Paradise Lost : “Better to reign in Hell,than serve in Heaven”.