"H" is for heaven. "H" is for hell. But the Big H, of course, is heroin, the pharmaceutical freeway between the two, at least for Mark Renton, Scottish junkie and amoral protagonist of Trainspotting.

Mark (Ewan McGregor) makes no apologies for his addiction. For him, it's a choice -- a "full-time business" he calls it. He tackles it as others would law or medicine, even when it takes his life figuratively and literally down the toilet. It has its ups and downs: Every time things start to go down, Mark cooks up.

His life is populated by an odd assortment of people, some of them junkies and some of them not. It makes no difference to Mark, though he's more at home with the junkies than the others. They share something. When we first meet him, he's decided to get off the stuff, though his reasons aren't clear, given that he describes the high as a thousand times better than the best orgasm you ever had. Even so, he does clean himself up, as does his friend Sick Boy, at least for awhile. But something always draws him back.

Trainspotting is a chilling film, made all the more horrifying by the calmness in Mark's voice as he describes everything from the crib death of a friend's infant to his own drug overdose and hospitalization. Even at the funeral of a friend, Mark seems more concerned with the details of the death than the implication -- despite the fact that it was Mark who started his friend on the drug that led to his HIV infection.

It's also a difficult film to sit through, though not for any of the usual reasons. It's thoughtfully scripted, crisply edited and stocked with a cast of unforgettable characters. More importantly, McGregor gives the performance of a lifetime as Mark, and cinematographer Brian Tufano goes to great lengths to show us a side of Edinburgh you won't find in any of the travel brochures. He's especially good at folding Mark's fantasies so seamlessly into the reality of the film that it's often hard to tell where we've crossed over. The effect is unsettling, to say the least.

Ultimately, Trainspotting is that rarest of things. A piece of literature on the screen, rather than one transferred to the screen. It works, despite the rigors it puts viewers through, because in the end it says far more than any of its characters do. That's partly because the characters are caught up in a whirl of self-denial, and partly because our estimations of them shift as the film progresses. Tommy (Kevin McKidd), the tower of strength, collapses; the hapless Spud Murphy (Ewen Brenner) emerges as the most human of all.

And we find wisdom in the words of a schoolgirl (Kelly MacDonald) whom Mark "accidentally" sleeps with during a brief period of relative sobriety: "The world is changing," she tells Mark. "Music is changing; drugs are changing." The words affect Mark. But is it for the better? Mark tells us at the end of the film that he's "a bad person." But is he? Or is he just one of us? It's just one more thing that makes Trainspotting the most frightening film you may ever see. Hard to watch, impossible not to.

Note: Trainspotting is rated R for graphic practically everything. And it's best taken without popcorn.

[ by Miles O'Dometer ]