You may have heard of the phrase “It does what it says on the tin”. Well the clue to the content of this film is pretty much in the title. Filth is an adaptation of a novel by Trainspotting author Irvine Welsh who also wrote The Acid House and Ecstasy both of which have also been brought to the big screen. Each of these Irvine Welsh stories has a common theme. They are all tales of abuse, drugs and displaced personalities and Filth is certainly no exception.

Filth is set in an extremely gritty modern day Glasgow (I remember when it was the City of Culture) and is far away as you can get from a tourist travelogue. James McAvoy plays Bruce Robinson a bent copper who is an alcoholic, drug taking sexual deviant and psychopath suffering from bipolar disorder. So just your average day at the office then? Bruce is up for promotion from Detective Sergeant to Detective Inspector but then again so are most of his colleagues. He sees the opportunity as a way to get his wife and daughter back but unfortunately he has an inability to form a long term relationship with anybody close to him.

To make certain that he is seen as the best and only worthy candidate he uses his scheming ways to scupper the other potential nominees by turning them against each other through lies and character assassination. He also sleeps with one or two of their wives.

The other police officers are an oddball mix of bigoted losers including the young and ambitious Ray (Jamie Bell), the equally determined and attractive Amanda (Imogen Poots), the thirty something GQ smoothie Emun (Peter Inglis) and the old hand Gus (Gary Lewis).

In amongst all these devious goings on there is also a racially motivated murder to solve and would almost guarantee fast tracking the officer responsible for closing the case.

Much of the dialogue is in the first person as Bruce looks into the camera and narrates his story (as per Michael Caine in Alfie). But as an audience we wonder how much of what Bruce says is true and how much is far removed from reality. It’s not long before we realise that Bruce is on a self destructive journey and regularly seeks the help of psychiatric specialist Dr. Rossi (Jim Broadbent) and even then, these visits start to become more and more surreal. Bruce is also haunted by the death of his younger brother when they were children and now regularly suffers hallucinations.

There is nice turn from comedy actor John Sessions as Chief Inspector Bob Toal who sees all the corruption within the department but turns a blind eye and would rather continue writing his movie screenplay which he hides under his desk. The talented Eddie Marsden plays mild mannered Bladesey a local wealthy and successful businessman who Bruce takes advantage of despite the fact that he doesn’t realise that Bladesey is probably the only genuine friend he really has.

In the midst of all of the doom and gloom there is some very funny laugh out loud moments. However, ninety percent of the film is certainly not for the faint hearted and it has its fair share of extremely violent outbursts and explicit sex scenes.

Mind you if that rocks your boat then this is certainly the film for you.

Director Jon S Baird keeps the pace moving and doesn’t allow the audience time to take their eyes off the screen. James McAvoy shows us a much darker and brutal side of his acting career than we are used to seeing and steals every scene. This is very much his vehicle.

It’s difficult to say that I enjoyed the film because of the serious and sometimes depressing subject matter but in a strange way I sort of did enjoy it. I always judge how much I like a film by the amount of time that I think about it afterwards and this film kept popping into my head. Not sure what that says about me?

Three and a half stars out of five.

Certificate 18 UK release October 4, 2013