John Landis must have entertained greater aspirations for his new movie, "An American Werewolf in London," than the dismaying results he's stuck with -- a wasted clever title and a minor fiasco destined for an obscure niche in the scrapheap of horror movies. Judging from the elements that do work -- a decomposing visitor from the beyond played by Griffin Dunne and the transfiguration sequence in which David Naughton's features are grotesquely altered by Rick Baker's astonishing and mechanically ingenious makeup designs -- the intention was probably a macabre classic in an offbeat tragicomic vein.

I suspect Landis hoped to keep moviegoers eerily disarmed with an unpredictable mixture of wacky and terrifying touches. Unfortunately, his own touch, as both screen writer and director, is so slack and uncertain that the movie ends up dramatically shapeless, a sorrier victim of disfigurement than the protagonist.

Opening today at area theaters, "American Werewolf" fades in on a lonely stretch of Welsh countryside and the sound of Bobby Vinton singing "Blue Moon." (It later amuses Landis to reprise recordings of the same standard by Sam Cooke and the Marcels.) Two American college students, Naughton as David and Dunne as Jack, are dropped off at a fork in the road by an amiable farmer. The young tourists adjust their backpacks and set off on foot to the nearest village, trading introductory small talk on their way.

Upon arrival they seek refreshment at a pub, The Slaughtered Lamb. However, they encounter a peculiarly hostile reception from the regulars and decide to leave abruptly. At this point the barmaid becomes concerned and suggests that, local secret or no local secret, the men can't let these unsuspecting lads take to the road on a night of the full moon.

Meanwhile, David and Jack have wandered off the road and become lost on the moors. Even worse, they're aware of being stalked by some kind of animal. With a snarl this shadowy predator leaps out of the dark and rips Jack to a bloody pulp. Panic-stricken, David takes to his heels. Recovering his nerve, he runs back to help his mortally injured friend and is also attacked by the beast. However, a party of villagers appears with lights and guns, and his life is spared.

David regains consciousness weeks later in a London hospital, where he's attended by an attractive nurse, Alex Price (Jenny Agutter), and a troubled, solicitous physician, Dr. Hirsch (John Woodvine). David learns that Jack's corpse has already been sent home for burial and that the circumstances surrounding the attack have been misrepresented -- the villagers have ascribed the murder to an escaped lunatic.

Still scarred by slashes and bites on the face and torso, David insists that the killing was the work of a ferocious animal, perhaps a wild dog. He's also subject to bizarre nightmares: In one he witnesses his family massacred by monstrous intruders in Nazi uniforms. Finally, he's confronted by the specter of his dead friend. The ghostly Jack, his face half torn away, informs David that they were assaulted by a werewolf and that David's injuries have transformed him into a werewolf. Unless he has the courage to take his own life before the next full moon, innocent people will die and join Jack himself as restless, decomposing spirits, cursed to wander in the domain of the undead.

David dismisses this warning as yet another nightmarish fancy. When the full moon rises, the warning proves all too true. David, now romantically involved with Alex and staying in her apartment, undergoes a monstrous metamorphosis and dashes out to commit mass murder in the night streets of London.

As a writer, Landis fails to endow David with character traits that suggest a peculiar susceptibility to monstrous influence and transformation. It seems unlikely that a beast of any sort lurks inside David Naughton, the cheerful young man from the Dr. Pepper TV commercials.

Naughton doesn't look haunted by gruesome experience or mental torment even after Dunne comes to haunt him. Naughton might have done wonders for the new Disney movie "Condorman," but his personality compounds the problem Landis creates for himself with a sketchy characterization. He's a pet, but the movie needs a pet who might also turn on you.

Landis seems to miss the symbolic significance of werewolf fables. Even the producers of a low-budget quickie like "I Was a Teenage Werewolf" had a more sophisticated perception of the genre. They portrayed their title character as a kid with resentments, the sort who might conceal an overpowering impulse to get even, to go wild. Far from being a suggestive figure, tragic or comic, Landis' werewolf is merely a nice boy who becomes a victim of misfortune. Details that first appear crucial, like David's uncontrollable fear when Jack is attacked, are ultimately reduced to insignificance, because Landis neglects to follow through.

Is Landis absentminded or just a poor writer? The behavior of the locals in The Slaughtered Lamb is inexplicable even after you know the secret the townsfolk want to hide. Landis doesn't catch something ambiguous; he just seems to waffle between the explicitly facetious and the explicitly ominous.

Given his identification with movie comedies such as "Animal House" and "The Blues Brothers," one may tend to misread Landis' intentions on the humorous side. Still, there are obvious stabs at comedy in "American Werewolf" that land way off the mark. Few routines could be feebler than the clumsy funny business invented to depict Don McKillop and Paul Kember as London policemen with incompatible personalities. An attempt at cute banter between Agutter and a little boy in the children's ward actually is feebler, and Landis likes it so much he does an encore. A puzzlement.

David's murder spree seems oddly ineffective too. Landis cultivates a new bad habit of stringing out the stalking of victims and then abruptly terminating the savage attacks by resorting to shock cuts, invariably cliches -- for example, a jangling telephone, a speeding train, a roaring lion in the zoo. Getting to be his own worst enemy, he seems to be losing his knack for comedy as he enlarges the range of his wrongheaded tendencies