Adam and Paul is a day in the life of two homeless junkies - called Adam and Paul - who wander round Dublin trying to get some cash together to score. It's a comedy, but beneath the laughs is a tragically compelling story of two lads whose lives are bleak almost beyond understanding.

I'm not a junkie, and not even from Dublin, but it seemed to me watching it that writer Mark O'Halloran and director Lenny Abrahamson have captured the situation pretty well. O'Halloran also plays one of the leads, with the other played by Tom Murphy. Both fit into the roles seamlessly, O'Halloran with a sly intelligence and Murphy with a gormless goodness.

You never learn which is Adam and which is Paul, until the credits. They only ever appear together. There used to be a third amigo - Matthew - but he has recently died, likely of an overdose. Adam is the leader, and Paul follows him, despite the abuse shouted regularly in his direction. But they get along grand, considering.

From the dialogue it is fairly obvious that the film-makers have seen Waiting for Godot. Adam and Paul share the same kind of pathetic helplessness and hopelessness as Vladimir and Estragon. As Adam and Paul traipse around Dublin the dialogue, between themselves and with others, is halting and repetitive and never really goes anywhere. Still it is skilfully written and seems spot on.

'Alright Adam and Paul?' 'Yeah alright' is about as far as human contact goes most of the time. They spend some time looking for whatshisname? The homeless guy thinks they mean Clank. Adam and Paul don't know who Clank is. It gets too confusing so they just move on.

The humour is similarly surreal. As well as jokes about wiping your arse with crisp bags, there are long scenes with clever, subtle gags which work better. The Bulgarian guy who is freaked because everybody always calls him a Romanian sponger is funny. Adam and Paul think he must be happier living on the streets here because Bulgaria is such a kip compared to Dublin. He snorts at this. He would rather be at home with his family, but he had to leave Sofia. "Was she pregnant?" asks Adam and Paul knowingly. The sequence where Adam and Paul keep sketch while their friends hold up a filling station, and fail to notice the Gardai arriving is brilliant. There has been talk of Laurel and Hardy and it is easy to see why.

Another stand out scene is where Adam and Paul decide to mug a kid who has down syndrome. They lure him from the bus-stop down an alley near O'Connell Bridge. While the kid looks at them and cries silently they rummage through his stuff. All that is in his bag is books and copies. He has no money, only busfare. Adam is angry and kicks the books around. Paul wants to help the kid put his books back in his bag. 'Will ye come on' shouts Adam. Paul shrugs and follows his mate. The appalling emptiness and futility of the whole thing is obvious.

This is far from the bright sunny Ireland of About Adam or Cowboys and Angels. Which is no harm. It is always drizzling, and Adam and Paul are filthy and cold. They spend most of the film hunched in on themselves, shivering from the cold and need for heroin, almost trying to roll into a little ball to protect themselves from everything and everybody. Dublin looks horrible. Even as they traipse around the shiny IFSC or cross the new Joyce bridge the city seems to mirror their desperation.

Some critics have dissed the film for not looking at the societal consequences of Adam and Paul's existence. This is bollox really. They are thinking of a different film. As they wander hopelessly around Dublin, attempting to steal a television or scabbing a can of cider off the sister of their dead friend, you never laugh with Adam and Paul, you laugh at them. Or at least you laugh for a while. By the end it gets harder and harder to see the funny side. It is very, very tragic, pathetic really. They are fucked.

One of the best Irish films in a long while.