George Romero has done it again. "Martin," an eerie, sardonic updating of the traditional vampire legend, should secure Romero's reputation as a modern master of the horror film. His "Night of the Living Dead," still unrivaled as the most imaginative updating of the zombie movie, was no fluke.

In the decade between these low-budget classics Romero had slipped back into obscurity while making three features - "There's Always Vanilla," "Jack's Wife" and "The Crazies" - that never got anywhere. Those setbacks haven't reduced his enthusiasm or proficiency. The nightmarish atmosphere, droll sense of humor and phenomenal visual inventiveness that impressed admirers of "Night of the Living Dead" return in "Martin" with undiminished force and originality.

Romero logically equates the mythical vampire with the contemporary sex criminal. In the opening sequence martin, a withdrawn, psychotic adolescent, claims his first victim, a young woman traveling on the same train. After picking the lock on her compartment door, Martin lies in wait, sedates his victim with a hypodermic, strips her and coordinates his sexual assault with the act of cutting open her veins and ingesting blood.

Martin has no supernatural powers. He's a furtive a rather forlorn little psycho, embodied with acurious mixture of half-creepy, half-plaintive ambiguity by John Amplas, a long-faced, slightly toothsome young actor who suggests Martin Sheen crossed with Pierre Clementi.

Unable to enter the dwellings of potential victims on batwings, Martin carries tools for breaking and entering. Unable to mesmerize or overpower victims, Martin relies on his hypodermic and remarks matter-of-factly at one point that satisfying his blook-lust was much harder before he learned to handle the needles. Lacking the necessary fangs, Martin must also carry a razor to sever veins at the climax of his crimes.

Martin knows a lot about his condition and would even prefer to cure or control it if only he could. Romero's most inspired humorous stroke is making Martin a nightcaller as well as a night crawler: He becomes an anonymous "regular" on an all-night radio show, phoning in to talk about his problems sincerely.

One of the things Martin knows is that the traditional vampire remedies are outmoded. He disembarks from the train in Pittsburgh to take up residence in the nearby, decaying mill town of Braddock. There a pious, superstitious old family patriarch, Tata Cuda (played by Lincoln Maazel, the father of Lorin Maazel), who considers him Nosferatu reborn, hopes to sequester him, accepting the obligation of confronting the family curse of vampirism.

Tata Cuda tries to coerce Martin with mirrors, strings of garlic, warning bells, crucifixes and even an old priest monotonously intoning rites of exorcism. These devices prove an annoyance rather than a threat. "It isn't magic," Martin declares contemptuously. "Even I know that." There is one traditional remedy remaining to Tata Cuda, and Romero allows him to resort to is as a way of resolving the story. After diverging in novel directions, Romero may not be justified in falling back on this particular convention, which underlines on of the major weaknesses in his plot - the apparent failure of the police to discover Martin's victims and begin investigating their murders.

However, exposition is never the film's strong point. Romero sustains the first half hour or so on sheer visual tension and ingenuity, but his resourcefulness may be more satisfying to movie freaks than casual customers.

One of the most interesting stylists ever to emerge from the sub-basement of low-budget exploitation movies, Romero imposes a vision that is not only distinctive but also witty and diverting. He has a genius for deriving baroque horror from banal raw material, symbolized most humorously by his use of Pittsburgh as a Transylvanian landscape.

Inspired by the traditons of the horror genre, Romero attempts to renew them by identifying an authentic form of vampirism amid ordinary, motley American surroundings. The effectiveness ofthis conceptual relocation is reinforced by the graphic boldness of his visual style. Romero's films may look tacky, but the superficial tackiness is transformed by a dynamic, expressionistic perception.

Romero is ominously brilliant with low angles, silhouettes, tight closeups and symbolic, foreshadowing inserts, such as fleeting images of a paring knife cutting a celery stalk or rainwater flowing down a windshield. Martin's second act of murder is a stunning setpiece, staged in a suburban home whose decor and geometry Romero has exploited with particular brilliance, while investing the situation with a startling twist.

The most effective single image appears at the start of this sequence: a chilling low-angle perspective of an automatic garage door rising.

Even the grainy, slightly bleached-out color seems appropriate, particularly when Martin remarks that while the sunlight doesn't deter him, it does tend to hurt his eyes. Romero often makes an artistic virtue of limited resources, but one would like to see what he could achieve with a modest budget, say $1 million-$3 million.

At 38, Romero is still young, robust and full of ideas about how the horror genre can be sustained.

It's apparent that Romero has as much to offer the form as Brian De Palma, with whom he shares many skills and perceptions. If he follows his muse conscientiously and declines to look back, the end result could be a formidable body of horror classics.