In 2089 Elizabeth Shaw, an archaeologist, chips through a cave wall in the bleak mountains of Scotland and finds out that the human race is not alone. Illuminated by her torchlight is a 35,000-year-old painting of people worshiping a giant, who is pointing to a cluster of stars.

The words "we're not alone" can be a doorway to either salvation or terror.

That is the knife edge on which the British director Ridley Scott has balanced "Prometheus," his long-awaited return to the universe that he first created in the 1979 movie "Alien."

"Prometheus," opening in the United States and around the world this summer, is the first science fiction film directed by Mr. Scott since "Blade Runner" in 1982 and his first in 3-D. The movie, with a screenplay by Jon Spaihts and Damon Lindelof, follows Shaw, played by Noomi Rapace (the girl with the dragon tattoo in the Swedish film trilogy), who, aboard the hubristically named spaceship Prometheus, uses an ancient star map to guide her to an obscure moon in the hope of meeting her maker.

Joining her are, among others, Charlize Theron as a chilly corporate executive; Michael Fassbender as David, an android of equally ambiguous talents and agenda; and Guy Pearce, who appears as Peter Weyland, the leader of an interplanetary conglomerate that owns the ship and much of the rest of the galaxy.

Web sites have been devoted to analyses of trailers, images and clues that Mr. Scott and cast members have let drop.

Among them is the Web site of Weyland Industries, with an ad for its new line of David androids and a talk by Weyland in which he lists technological achievements, including the ability to make robots indistinguishable from humans. "We are the gods now," he announces.

Uh oh.

In Greek mythology Prometheus was chained to a rock and had his liver eternally pecked out for stealing fire from the gods and giving it to humans.

On the phone from London, where the film was mostly shot, Mr. Scott said that "God doesn't hate us," then added ominously, "But God could be disappointed in us - like children."

"Prometheus" was not a prequel to "Alien." Mr. Scott said he figured the "Alien" franchise was finished. Then, three years ago, he thought there might be a way to "rescue" it, as he put it.

In "Alien," the unlucky crew finds a derelict spaceship, and in the pilot's chair is a giant humanoid being with an exploded chest. Then a strange egg opens up and wraps itself around the face of a crew member, played by John Hurt. "Once John Hurt looks into that egg, the film took off," Mr. Scott said.

But he was surprised nobody ever asked him about the being in the pilot's chair. "Who was he? Why did he land there?" Mr. Scott wondered. And why was he carrying a cargo of such "wicked biotechnology"?

He thought James Cameron, who directed the first sequel, "Aliens," would address the question. But the enigma remained, and in the process of developing it, he said, "a grand new mythology" emerged.

On the one hand, he said, he was inspired by the quest to look for life beyond Earth.

At the other end of the credibility scale is the pop archaeologist Erich von Daniken, who argued in books like 1968's "Chariots of the Gods" that there was archaeological evidence in the form of things like the Nazca lines in Peru that visitors from outer space helped along life on Earth.

Have we been previsited by gods or aliens? "The fact that they'd be at least a billion years ahead of us in technology is daunting, and one might use the word God or gods or engineers of life in space," Mr. Scott said.

And would we want to meet them again? The cosmologist Stephen Hawking has suggested we should be careful Out There: "We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet."

Behind the Prometheus legend is the idea that "the gods want to limit their creations; they might want to dethrone God," said Mr. Lindelof.

"I hope no one thinks we are overly pretentious," he said. "We set out to make something entertaining and thrilling to watch, not a band of people sitting around talking about the meaning of life."