WARNING: SPOILERS

The first half of Ridley Scott’s “Prometheus,” a prequel to Ridley Scott’s 1979 horror masterpiece “Alien,” raises some fun and intriguing questions. The second half gives us some lame and unsatisfying answers. It’s a smart sci-fi film that gets dumb fast.

In the latter part of the 21st century, archeologists Elizabeth Shaw and Charlie Holloway (Noomi Rapace and Logan Marshall-Green) stumble upon 5,000-year-old cave paintings from different parts of the world that include the same image: a giant man pointing to a five-planet solar system that isn’t visible from Earth. This solar system has a planet, or a moon, which is semi-inhabitable for humans, although its atmosphere, we’re told, would be like sucking on an exhaust pipe. Meaning in 2093 we’ll still have cars with internal combustion engines. Bummer.

But, badda-bing badda-boom, a mission to this planet, funded by the Weyland Corporation, is underway. We see the ship, Prometheus, en route, with its 16 human crew members in stasis, while its lone android, David (Michael Fassbender), studies ancient languages, shoots baskets while riding a bicycle, and watches both the dreams of Ms. Shaw and David Lean’s “Lawrence of Arabia.” He styles his hair in the fashion of a young Peter O’Toole and quotes one of the movie’s more famous lines: “The trick, William Potter, is not minding that it hurts.” Apparently even our robots want to be like movie stars. Or so the movies tell us.

A few months ago, online, I saw a clip from “Prometheus,” in which Weyland Corp. founder Peter Weyland (Guy Pearce), in 2023, gives a TED talk. It’s a good clip, although the “talk” doesn’t quite hold together:

So Weyland expounds on “Lawrence” and “not minding”; on the titan Prometheus, who gave us fire (and thus life), and who was punished by the gods by having an eagle rip out his stomach and eat his liver every day for eternity; and by the fact that, in creating androids, in creating life, “We are the Gods now.” But this clip didn’t make the movie. Too bad. The talk doesn’t quite adhere but the scene provides connective tissue for the movie. It lets us know why, for example, David is watching “Lawrence,” and how, for example, the giant men in the cave drawings might be ancient aliens thought to be gods, and how, for example, the legend of Prometheus, with his ripped-out stomach, might be our first “Alien” story. I.e., it wasn’t an eagle ripping into a stomach; it was an alien ripping out of it.

As in “Alien,” as opposed to the optimistic “Star Trek” world, there are class distinctions aboard Prometheus, and, as in any corporation, a battle for power. Who’s in control of the mission? A hologram of a wizened Peter Weyland (Pearce in make-up) tells the crew that the scientists, Shaw and Holloway, are in charge, but the robot-like Meredith Vickers (Charlize Theron), who, out of stasis, does push-ups while those around her are regurgitating, and who has separate, lavish quarters, obviously objects. Then there’s the captain of the ship, Janek (Idris Elba), but he seems to know his place as employee and glorified chauffeur. “I’m just the captain,” he says more than once with a smile.

There’s also David, who, like almost all androids in sci-fi movies, has ulterior motives.

So they land, quickly find the alien stronghold, along with giant, godlike images of humanoids (thank you, H.R. Giger!), and evidence of a massacre: bodies piled high by a doorway. But they insist on poking stuff, goo and slime, that we know better not to poke. We, viewers of countless “Alien” movies, know what’s going to happen. They don’t.

Well, some do. David, for example. How does he know? Is he literally reading the writing on the walls?

It all comes apart fast—both mission and movie. Two scared scientists who are left behind, the Shaggy and Scooby of the crew, come across a snake-like alien life-form emerging from a blackish goo, and one insists on practically cooing to it. Bad move, Scoob. It, of course, wraps itself around his arm, breaks it, and when the other scientist tries to cut it off, he gets the alien’s acid-blood sprayed in his face. In seconds, both are mangled toast.

Meanwhile, David has mixed some black goo into the drink of Holloway, who, inexplicably, is distraught that in a few hours time in the alien stronghold they didn’t uncover the secret to life. This guy’s a scientist? Doesn’t he know the slow, plodding nature of the discipline? Earlier, Shaw calls the aliens in the cave painting “engineers,” and assumes, without evidence, that they engineered us. When asked why she assumes this, she echoes her father’s comment about why he believes in an afterlife: “It’s what I choose to believe,” she says. She might as well be a Young Earth Creationist.

Holloway perks up when Shaw informs him that the DNA she recovered from the site matches human DNA exactly, and the two celebrate the way humans do, with booze and bed, but the next morning his eyes are red and he doesn’t feel himself, and during the mission to the site he bends over and his skin starts breaking apart and he pleads to be killed. Vickers, who doesn’t want to be contaminated, obliges. Everyone, it seems, has their agenda. Hers is staying clean. She seems to know instinctively that there’s bad shit out there.

Back on the ship, just after seeing her lover torched in front of her, Shaw is informed, by David, almost maliciously, that though she thought herself sterile, she is in fact pregnant. Three months along. How is that possible? Oh, we know how it’s possible. And we know it’s not human. At which point we get the film’s best, most harrowing scene: Shaw performing computer-aided self-surgery to remove the alien before it gets all Prometheus on her ass (or stomach). There’s a great tension between a sense of urgency (hers and ours) and the computer’s decided lack of it. Once she survives, freezes the alien life form, and makes her way, stumbling down the hallway with a stapled stomach, I, like most in the audience, realized, “Right. She’s this movie’s Ripley.”

This takes us to the third act, where we discover that a) Peter Weyland is alive and on board, b) Wickers is his daughter, and c) David has uncovered a chamber where a giant humanoid lies in stasis. That’s why Weyland is there. He’s hoping to meet his maker.

He does. Awakened, surrounded by puny humans, the giant humanoid listens as David talks to him in what we assume is his own language. Whatever David says, it enrages the giant, and David loses his head (literally), and Weyland meets his maker (figuratively), and the humanoid, with whom we share DNA, starts up his massive, c-shaped spaceship, still working after all these years, to bring it, and stomach-popping aliens, to Earth.

Apparently the giant humanoids are developing these aliens like weapons of mass destruction for the purpose of... wiping us off earth? So they can populate it? Or something? They’re not our engineers, in other words; they’re our engineers of destruction. “We were so wrong,” Shaw says.

She figures all this out pretty quickly, informs Capt. Janek that he needs to stop the alien ship or “There won’t be any Earth to go back to,” and, amid lines of bravado, which they snort like lines of cocaine, he and his remaining crew perform a kamikaze mission and bring the alien ship down. The crashing ship promptly crushes Vickers, who has jettisoned onto the desolate planet in a desperate attempt to survive, and nearly crushes Shaw, who rolls out of the way in time.

So is she the sole survivor on this desolate planet? Nope. The giant humanoid survives as does one of the stomach-popping aliens; and she gets away from the former by releasing the latter.

So now she’s alone? Nope. David, head removed from body, is still functioning, and he informs her there’s another alien ship, which he can pilot. But she doesn’t want to go back to Earth. She wants to go forward to the planet of the giant humanoid aliens. She wants to learn more. As do we. In this way the prequel sets up a sequel that doesn’t lead to the original. Two stories diverged in a movie, and she, she took the one less traveled by, but we don’t get to see if it makes all the difference for another two years or so. Thanks, Ridley.