Marlene Detrich, studying Orson Welles' palm near the end of "Touch of Evil," tells him half-teasingly, "Your future is all used up."

"Blade Runner" (selected theaters) takes place in that used-up future: Los Angeles in the year 2019, a dense and ominous metropolis. Everyone who can afford to has moved to space colonies, or to other forms of off-world living. The Japanese and Latinos have tipped the population balance in their direction; Broadway, with most of its glowing neon signs in Oriental characters, looks like the Ginza at rush hour.

The streets are dangerous places to be and the air spaces between the buildings are almost worse. They teem with "spinners" cars that whoosh upward and drift to rooftop landing slots as easily as they can maneuver the city streets. The language is cityspeak, a gutter mixture of Japanese, Spanish, German and what-have-you. And a semipermanent inversion layer drenches the occupants in a nasty, gritty, constant rain.

Director Ridley Scott and his entire creative cadre have made an extraordinary-looking film that combines film noir and science fiction to probe a world where you can no longer tell who's human any more. Every detail of the film's environment is so seductively, splendidly designed that it feels emperor's new clothes-ish to point out that there is embarrassingly little else to the film.

It has almost a one-sentence plot, a dogged chase by ex-cop Rick Deckard (Harrison Ford), reluctantly pressed back into service as a blade runner, a sort of legalized bounty hunter who can identify and "retire" defective replicants.

It isn't easy, since replicants, the future's doers of dirty jobs, look exactly like humans and have human, not robot parts. They are genetically engineered humans, made and sold as slave laborers, miners, soldiers, space explorers and ladies no better than they should be. While they seem to be re-created in a range of ages and IQs, they have one thing in common: a four-year life span.

(Don't let the words blade runner confuse you into expecting a super-high-speed chase film. Blade crawler might be more like it. )

Most of the world's replicants come from the Tyrell company, a 700- story black pyramid that floats above Los Angeles. One of the film's seven (70? 700?) wonders, it looks like a Mayan temple as built by Louise Nevelson.

It seems that four replicants from Tyrell's top-of-the-line Nexus Six series have turned dangerous, running amok off-world and killing 23 people. The replicants, whoni Deckard must find, are Leon (Brion James), a large military type, fast on the trigger, low on the intelligence scale; Zhora (Joanna Cassidy), an exotic dancer whose specialty is assassination, and Pris (Daryl Hanna), a "standard pleasure model" for use among the military. An acrobat with a dandelion-fluff blonde mane and eye makeup that gives her a raccoon mask, Pris is endearing and lethal all at once.

And finally there is Roy Batty (Rutger Hauer), barrel-chested, with the strength and speed of an Olympic athlete, cunning, intelligent and poetic. It is in mortal combat with Batty that Deckard theoretically learns about the preciousness of life; Batty, because of his desire for life, is actually more human than the film's humans.

In the film's single most beautiful sequence - inside the Tyrell pyramid, looking out at a golden setting sun - we meet Rachael, Dr. Tyrell's special assistant and his special pride. She may seem hardly less un-human than the average high fashion model; however, Rachael is rep!icant through and through. (Newcomer Sean Young looks like a mixture of Vivien Leigh and Martha Vickers when she played the nymphomaniacal baby sister in "The Big Sleep.") Like others of the Nexus-Six series, she has been gifted with a memory implant to cushion the shock of her non-humaness.

The inner question of "Blade Runner" is "What defines a human?" (The screenplay, by Hampton Fancher and David Peoples, is very freely adapted from the late science-fiction master Philip K. Dick's "Do Androids Dream of Electric Sheep.") . But our chief human, Deckard, was called "sushi" by his ex-wife. Cold fish. And the film is brilliant in its sleight-of-hand; its amazing surfaces catches us before we notice that the plot doesn't answer its own questions.

If the story is frail and unhelpful, to put it politely, it is certainly drenched in atmosphere. "Blade Runner" may attract two and three-timers to savor its inventions. These devices come so abundantly they're almost throw - aways.

And since director Scott, who began as a scenic designer, has always had a superb eye, it's no surprise that "Blade-Runner" is an exercise in visual sensuality. It has the palette and the sense of decadent, controlled chatter of Polaroid artist Maria Cosindas; the necrophiliac chic of photographer Deborah Tuberville. There is something in it of Joseph Cornell's magic boxes and something more of a Vermeer or a Rembrandt still life. It draws on Frank Lloyd Wright and Charles Dickens equally.

Collaborating in this heady wonder were cinematographer Jordan Cronenweth, art director David Snyder, special-effects masters Douglas Trumbull, Richard Yuricich and David Dryer, with matte artist Matthew Yuricich, and Syd Mead, a "visual futurist," whom Scott chose to think through the near-future's look.

The film's sense of impending doom, however, is all Sir Scott. It hung over "The Duelist"; it most certainly permeated "Alien." In "Blade Runner" it is everywhere. You are so braced for a particularly nasty kind of evil that you search every cier of every gorgeously cluttered shot for new danger to come. Frequently you are rewarded: "Blade Runner" has periodic eruptions of particularly nasty violence (its R rating comes from these bloody explosions). The continuing threat, however, is so exhausting that you finally resent being frightened all the time.

There is occasionally whimsy and charm among the fright, although it certainly doesn't light up the Rachael-Deckard romance. A little, sickly genetic designer (William Sanderson), who befriends the waifish Pris, has his quarters in the Bradbury Building and they resemble a cross between Gepetto's workshop and Miss Havisham's wedding decay.

The actors, the hardware and the imagination are top drawer. Every technician on the film can be deeply proud of his or her contribution; but that this much craft and dedication is at the service of such a wafer-thin story is sad. Their magic deserves more than a close examination of people who cannot feel anything - by birth or by design.

By Sheila Benson
Times Film Critic