It was the most commercially successful British film of 1995 and a major turning point in our film industry. It was the first movie of its director (Danny Boyle), producer (Andrew Macdonald) and writer (John Hodge). They kept working together and made Trainspotting, A Life Less Ordinary and The Beach, while Boyle of course is now an Oscar-winner thanks to Slumdog Millionaire.

It also gave starring roles to three relatively little-known actors: Ewan McGregor (in only his second movie), Christopher Eccleston and Kerry Fox. Two of those have since become a great deal more famous. If you ever wanted to watch the Doctor point a power tool at Obi-Wan Kenobi's forehead, this film is for you.

Super-quick plot summary: three flatmates in Edinburgh recruit a fourth flatmate who unwittingly bequeaths them a suitcase full of money.

The interesting thing about this one is that I was mildly reluctant to rewatch it. I'd seen it in the cinema in 1994. I knew it was good, but I wasn't expecting it to be much fun. You see, it's a jet-black piece of nastiness with deliberately unlikeable characters. The film had been going to be called 'Cruel' and the people behind it had a list of things they wanted to do. To quote Boyle, they wanted to ditch "the moral baggage that British films carry around all the time." They didn't want to be sensitive. Again quoting Boyle, it's "not about class or society, or people being crushed by forces they can't control. Everybody takes responsibility for their decisions. We didn't want this film soaked in British social realism." (Mind you, after saying that he's since backtracked a bit, having noticed that the money-grubbing selfishness of the plot can be read as a reflection of post-Thatcherite Britain.)

Also, now quoting McGregor, "The accepted rule is that you have to sympathize with the leading characters, but we wanted to break the rules."

That last one's the big one. These aren't people you'd clasp to your bosom. A lot of people had a problem with that and it has to be said that this is a cold, black-hearted film. It takes a joy in being horrible that's reminiscent of Alfred Hitchcock and I can't really say I cared what happened to any of the characters... but despite that, I found the film quite watchable.

1. Ewan McGregor's character is vile. He's like a hyena on its hind legs. He humiliates people for laughs and doesn't care about anyone. After he's suggested dismembering and mutilating the corpse of their flatmate, he's genuinely surprised when both Eccleston and Fox get queasy. He talks through the speaker at a charity event for children. He opens his flatmates' mail and reads them. You'd pay money to punch this man in the face... and yet Ewan McGregor's charm makes him watchable. He's fun to watch, partly because every so often something violent will happen to him and you'll cheer and laugh. Being punched in the face? More, more! Having his head wrapped in a plastic bag as a gangster beats him with a crowbar? Nice one, mate! Hit him harder! Being nailed to the floor with a kitchen knife? Biggest laugh in the movie.

He's like a villain, basically. He's a witty, horrifying villain who also happens to be one of the movie's protagonists. (I refuse to say "hero".) The film's not trying to pretend that he's likeable or anything, so no problem. My only problem with McGregor is... well, McGregor. I'm not a huge fan of his as an actor. He seems like a really nice guy and he always seems genuine in his films, but I haven't always sensed much beyond that. He lacks that top gear that you'll get from great actors and film stars, that ability to lift their character to be the most fascinating thing in the world. Here, he's charming and made me enjoy watching a character who could have been unwatchable, but on a technical level I don't think he's doing enough with the dialogue in, for instance, "alive, dead, dead, alive. that sort of thing. It wasn't difficult to spot." I didn't buy his transformation into a good-ish guy in the all-carnage finale.

In fairness, McGregor is in only his second film role of his career and is pulling off a crucial, difficult trick. He'd repeat it in Trainspotting. However I think he's the weakest of this film's three leads.

2. Kerry Fox has drawn the short straw, I think. It's a good role, but it's not a great one. Her character's a bit bland, isn't she? McGregor's playing the bastard and Eccleston's playing the polite, repressed guy who cracks and starts using power tools on people, but Fox is, um... well, she gets her flatmates to say "she's not in" to incoming phone calls. That's it, really. She's the normal one. If it was her who got away with the money at the end, that would be the least immoral ending.

Fortunately Fox is bringing her character alive so well that such thoughts don't occur to you. She's very good. In fairness her character does descend into corruption, although it's understated compared with....

3. Christopher Eccleston. Oooooh, Eccleston. It's his film, I think. He's the one who gets the huge character arc. The other two don't really have a problem with being bastards, but Eccleston's the one whose reaction is to do the right thing. "No," he says without a second thought when McGregor proposes that they cover up a death for profit. "No," says Fox, but without conviction. "Yes," says McGregor.

The tragedy of Eccleston's character is that he's not strong enough to stand up to the other two. He's never done any of this before. When he almost tears that guy's head off at the charity event, he then shrinks back into himself afterwards because he's never done anything like that before. He's a chartered accountant. He's reliable. He's the one with good instincts. "Unfeasible. You mean immoral." He tells McGregor that he won't be able to cope with being the one who does the mutilation... so of course it ends up being him and his prediction comes 1000% correct. You've got to love the moment where he asks "is that going to be deep enough?" as he's doing stuff that makes his stomach turn. He's been landed with the unspeakable job. McGregor and Fox have it easy, digging the grave, but we know from the movie's title that they won't even be able to do that properly.

We know Eccleston can do intensity and moral fury. Here though he's doing that in the context of a timid, well-intentioned character who lets himself get pushed beyond his limits. He'll be scary, but he's also pathetic. He's no saint, mind you. He's laughing along with everyone else at McGregor's abuse of that nice ginger bloke at the beginning, for instance. However it's him who carries the film and I loved every moment of his descent into attic-dwelling madness. Everything he does to anyone in the flat is the consequence of their own bad decisions earlier and he's their just deserts made flesh.

My favourite touch in the film, though, is Ken Stott's Detective Inspector McCall. It's not afraid to drift away from naturalism. There's a touch of absurdism in his dialogue, making the character threatening, intelligent and funny all at once.

The film's acutely aware of genre. It has scary gangsters. It has nauseating sound effects. It has lovingly photographed power tools instead of guns, since this is Britain. It has striking images, like the beams of light in the attic from the holes in the ceilings below. Above all, though, it's delighting in its own callousness. There's a popular theory that McGregor's character dies at the end, although it's not shared by Boyle and indeed the line of McGregor saying hello to the detective was added in post-production as an attempt to prove that he's still alive. I don't buy the theory myself, partly because it's never occurred to me at any time I've viewed the film, but partly also because I think to kill McGregor would be to diminish the film's gleeful amorality. If everyone loses, then greed has been punished and it's a moral film. The director's intended ending, on the other hand, is dropping its trousers to morality and handing victory to the bastard.

Bit of trivia. According to Danny Boyle, there's a connection between this film and Trainspotting. Keith Allen plays a drug dealer in both films and these might be the same character, since both films happen in Edinburgh and Trainspotting is set during the 1980s while this is 1994.

This isn't a warm film, although it's more fun than I thought it was going to be. It's horrible, but in a witty, entertaining way. You want to see horrible things happen to its protagonists, so it probably counts as a miracle that the film's watchable. There are many good things about it, but I think its heart and soul is Eccleston's. He goes from the voice of morality to an anti-troglodyte. (Troglodytes live underground or in caves, but Eccleston's in the attic.) It's bursting with savage, malicious energy. Even compared with Boyle's full impressive filmography, it more than holds its own.

"But Juliet, you're a doctor. You kill people every day."