Prometheus – for a film which is not a prequel to the Alien franchise no honest well okay maybe it is – appropriately asks a ton of questions. Sadly, it either ignores them or gives dumb answers that don’t stand up to a second’s scrutiny. Having said that, as a film, it looks great. Pretty pictures, after all, trump everything.

The movie opens on a verdant planet beside a waterfall. There is a giant hairless humanoid standing on the shore, and a giant flying saucer hovering in the sky nearby. The giant opens a small container and eats its contents. It kills him. He falls into the water and his body dissolves down to its constituent DNA. This, we are supposed to believe, is an alien seeding human life on Earth.

But wait.

Did the giant humanoid mean to dissolve into primordial goop? Was it suicide? Or a really badly planned delivery method for planetary seeding, in which someone has to commit suicide? Maybe it was murder, maybe that was humankind’s original sin. But if we’re descended from them, why did we evolve to be so short and so hairy?

Cut to the Isle of Skye, later this century. Two palaeontologists have discovered 35,000-year-old cave paintings in a, er, cave. These paintings depict a giant pointing to a pattern of five circles. If it’s the same giants from the flying saucer, then they must have returned to Earth. Why? So they could prompt Upper Paleolithic humans to paint their picture? (We’ll ignore for the moment the fact that the oldest settlement so far discovered on Skye is younger than these cave paintings by about 30,000 years.)

This painting of a giant pointing the way to a pattern of five circles is apparently not unique to Skye. In fact, variations on it appear on artefacts from a wide variety of ancient civilisations, not all from the same time period – suggesting a number of visits, or a stay of a couple of millennia. This, apparently, is sufficient evidence for the two palaeontologists, Shaw (Noomi Rapace) and Holloway (Logan Marshall-Green), to persuade zillionaire Weyland to fund a mission to the “galactic configuration” represented by the five circles. “Galactic configuration”? What’s that then? A planetary system? Or a constellation of five stars? As seen from Earth? Thirty-five thousand years ago? Stars move, you know. Planets move too. Over time, their positions change – and so too does our viewpoint, as the Earth itself moves.

No matter. Movie logic says there’s something in the heavens which can lead our intrepid palaeontologists to a specific planet. Well, actually a moon of a gas giant. We’ll ignore the vast amounts of radiation the gas giant is likely producing, or its magnetosphere has trapped – this is a movie, after all. Weyland’s spaceship – called the Prometheus – lands on the moon, LV-223 (the first two Alien films took place on LV-426).

All this is handily explained in a briefing given by Shaw and Holloway to the members of the mission aboard Prometheus. However, rather than hire competent scientists for this trip, Weyland appears to have chosen to use rejects from Central Casting. It’s bad enough that the two leaders, Shaw and Holloway, believe in some von Däniken-type rubbish about gods from outer space creating humanity, but the rest of the team are no better. One tells another to fuck off when he introduces himself. Right. You’re zillions of kilometres from Earth – not “half a billion miles,” as one character later says; that would put you about twice as far from Earth as the Moon. Anyway, you’re light-years from Earth, in a spaceship with a small group of people, en route to an alien world. It is not a good time or place to act like an arsehole.

So there’s the scientific mission, the crew of Prometheus, the representative from Weyland, named Vickers, and an android, David. Vickers lives in a “lifeboat”, which is like a luxury flat stuck on the back of the spaceship. This lifeboat also contains a “medpod” – like the original Alien‘s “autodoc”, I imagine – but this one only works on human males. Er, right…

Prometheus lands on LV-223, and discovers a row of strange giant buildings. They’re like giant weathered pyramid-things, inside circular walls. Shaw and the others explore the nearest one. It contains lots of tunnels… and a room with a giant humanoid head. Also jars, lots of jars. Which start to ooze black gunk once the room is breached. Later, they determine the pyramid is a tomb.

Except most tombs don’t have spaceships buried under them. And these are the Giger boney boomerang spaceship from Alien… and the space jockey proves to be one of the giant hairless humanoids wearing a spacesuit. Which does make you wonder why they turned up to Earth in a giant flying saucer.

The boomerang spaceship also contains lots of jars, which the scientific team realise are a weapon. But a very strange weapon. It has different effects on different people. It made the giant at the beginning of the film turn into gunk, and so seeded the Earth. It makes the preserved head of a giant they find in the tomb explode. It turns one of scientific team into a super-strong diseased madman. It allows Holloway to impregnate Shaw with a tentacled monster. (She later uses the medpod to extract it – clearly it has been programmed to deal with pregnant males.)

When they find a surviving giant humanoid, and David manages to speak to him because he’s studied comparative linguistics and can somehow cobble together a working patois of the alien language from that… well, you don’t need that alien gunk to make your head explode. (Oh wait, maybe human languages are genetic too… Not.) But by this point in the film, the plot has already imploded into a black hole of illogic and nonsense and implausibility, so you only have yourself to blame. Prometheus is not a film to watch with your brain engaged. Just admire the pretty visuals. It makes for a much more entertaining 124 minutes.

Yes, Michael Fassbender pwns the film as the android David. Noomi Rapace’s character makes little sense, not least because religion has been fisted into a story it doesn’t fit. The rest of the cast might as well have worn red shirts. Vickers (Charlize Theron) tries to do a robot-or-not thing, but in the end proves she’s human the only way a woman in a movie possibly could: she fucks the captain (Idris Elba). At one point, Shaw is referred to as Holloway’s “zealot girlfriend”. Shaw and Vickers, incidentally, are the only two women in the film. So by 2093, we’ll have cool interstellar spaceships, but no gender equality. Plus ça change…

I saw Prometheus on IMAX 3D. It cost me £13. It was not worth it. I should have waited for the DVD and rented it. I also saw John Carter on IMAX 3D. That film was worth it. John Carter was a much better film. It also flopped. It’s unlikely Prometheus will flop – in fact, it’s probable the sequel implied by the ending will be made.

If you want to see a good sf film with giant spaceships and scary thrills, watch Cargo.