The porn star John Holmes, aka Johnny Wadd, is famous for one thing, but happily, “Wonderland” is not about that one thing. In fact, that one thing is more or less incidental to the story it tells.
Instead, it’s about crime, murder, deceit, narcotics, the hustle, the DTs, love, pain and earning Val Kilmer an Oscar nomination. Basically it follows a small-time addict, who was once a famous porn star, as he plays various factions in the early-’80s Los Angeles demimonde against each other until serious blood has been shed, but not his. Then he runs away.

As unappetizing as this may sound, it’s even less appetizing in James Cox’s film, which looks at Holmes’s possible involvement in what were called “The Wonderland Murders” in 1981 with all the high seriousness of a biblical scholar studying the miracle of the loaves and fishes. It’s mostly for connoisseurs of excessively violent, meaningless crimes involving minor cult figures; or for students of arterial spatter patterns and what truths they reveal.

Why does this film exist? Sometimes there is no why, there’s only a how. This is how: overblown, overheated, overdirected, overacted, overlong and over here, in the local bijoux. Cox never wants us to forget this is a movie, and so he crams the frame with tricks, as if he considers us all in terminal attention-deficit. Split screens, slow-mo, fast-mo, overexposure, underexposure, everything but the kitchen sink and the editing console. The movie screams with a young director’s need to be noticed, as it screams with Kilmer’s parallel need in the showy doper/porn star role. And all one feels is the urge to shout back: Shut up, I hear you. Now go away.

“Rashomon”-like, the movie chronicles Holmes’s behavior over the day of the crime, from a variety of points of view, allowing viewers, if any are left, to make up their minds on the level of his involvement. It consciously changes camera styles to suggest mind-set: Thus, when Holmes is telling the story, we are in the jittery, jiggly junkie’s brain, with nothing clear or focused, with a sense of all things being sublimated to the fact of the giant hunger-rat eating at the soul. Later, when we’re with the cops, the cameraman mounts his instrument on an actual tripod, and things settle down. This has been done about a thousand million times before, so it’s pretty much a wash, artistically.

The film begins with Holmes, strung out and now unemployable in the porn industry after the great days of the ’70s, falling in with a violent but small-time outfit out of that weird zone where porn, dope, biker culture, smoking and tattooed women intersect. The group consisted of a biker (Dylan McDermott, cast against type), a hippie (Tim Blake Nelson), a cowboy (Josh Lucas, the next Woody Harrelson) and their various women.

It’s a signifier of the film’s editorial confusion that three relatively name actresses — Christina Applegate, Natasha Gregson Wagner and Janeane Garofalo — play the three girlfriends, and are all but edited out of the film. None of them has a single line, except for a brief close-up on Garofalo, who proclaims, “Down with U.S. Imperialism and the Anglo-American War on Democratic Iraq.” No, she doesn’t, but isn’t it pretty to think so?

The details are too complex to chronicle: Roughly, hoping to win favor with the small-timers, Kilmer’s Holmes takes some stolen antique firearms to big-time crook Eddie Nash (played in stage-villain accent by Eric Bogosian) to exchange for drugs. But he rips them off; to get revenge, and to get drugs, the three men, with Holmes’s help, rob the guy in his mansion.

Like, duh! This was not the crime of the century. Professor Moriarty, Ernst Stavro Blofeld and Keyser Sose weren’t involved in the conceptualization, and little boys shouldn’t pick on big boys unless they can take those big boys. These little boys couldn’t, were quickly tracked down, and were dealt with by applications of lead pipe to cranium. Ugly stuff.

The issue then was to what degree Holmes had aided and abetted both sides, and two cops, played by the great Ted Levine (you remember Buffalo Bill in “Silence of the Lambs”) and Franky G try and sort it out. They only learn that it can’t be sorted out and that, really, nobody cares. Scum swindle crud; crud crushes scum; end of meaningless story and onto the next day’s fresh atrocity.

Cox does have one idea he believes compels the otherwise loathsome Holmes to our attention, and that’s his odd domestic situation. Holmes was married to a decent woman, a professional nurse. When he entered porn, the two separated but never divorced, and they remained on good terms. Later he took up with a 15-year-old girl, and his wife, Sharon, weirdly came to feel like a mother to her. (Needless to say, everybody here was the product of a wretchedly broken home.)

Thus the movie’s strongest performance is Lisa Kudrow’s as Sharon Holmes, an unglamorous, unsexy, unfunny turn as a woman of solid virtue who somehow offers the unreliable Holmes his only mooring in a turbulent world. Yet she cannot forgive or forget; her final mission is geared toward saving what is savable, mainly the young Dawn (Kate Bosworth) from the horror that seems to follow Holmes everywhere he goes.

The movie is somewhat like watching germs in a microscope. You never knew they were there and now that you do, you wish you didn’t.