Ridley Scott’s Prometheus is the best kind of failure. Visually confident and philosophically perplexing, it will invite discussion in spite of its flaws. In early interviews about the film, Scott gave the understatement of the year by saying, “[it] shares strands of Alien’s DNA, so to speak.” This quasi-prequel does not just share DNA with Scott’s breakthrough film; it shares most of its genome. Scott’s bigger problem, and what undermines Prometheus at every crucial point, is the weirdly undeveloped script by Jon Spaihts and Damon Lindelof.

There are tropes of the Alien franchise that fans demand, and the screenwriters provide them as if going through a checklist. A group of men and women are in cryosleep as they hurdle through space toward a distant planet. David (Michael Fassbender) need not rest since he is the sole robot on board the Prometheus, so he passes the time by watching Lawrence of Arabia, dribbling a basketball, and learning every conceivable ancient language. After waking up, scientists Shaw (Noomi Rapace) and Holloway (Logan Marshall-Green) tell the crew how they plan to meet mysterious giants, nicknamed “Engineers,” who may have jump-started humanity on Earth. The lecture is similar to Ripley’s from Aliens, except they treat the creatures with reverence instead of implacable hatred.

The scientists make ominous discoveries on the planet, which looks like a modern LV-426, and and they actually have time to think about what they see before the mission goes awry. Characters behave like conduits for the audience: Holloway is disappointed, Shaw is excited, and the lesser scientists are utterly terrified. Back on the ship, the captain (Idris Elba) and a cold corporate functionary (Charlize Theron) provide running commentary, debating the purpose of their journey. Scott dwells on the darkly sinister imagery, giving the audience the promise of something extraordinary with innovative set-design and top notch effects. The CGI never calls attention to itself, and by serving the story, these early scenes are where Scott best engages with our sense of wonder.

Once all hell breaks loose, as it must, the plot then splinters into disarray and never quite recovers. One of the best things about Alien is the terse economy of Dan O’Bannon’s writing. There are few characters and the conflict is always clear, so Scott could easily blend raw suspense with sci-fi intrigue. Spaihts and Linelof, on the other hand, construct a string of effective scenes that never coalesce. In terms of basic plot logic, Prometheus is an utter mess. Characters have separate discoveries about the planet, only to reunite as if nothing has happened. Shaw’s Engineer theory is forgotten by the climax, and David’s agenda shifts to whatever the script requires of him. Missteps like this would not be deadly for a less ambitious science fiction film, but these screenwriters insist upon their own significance with half-baked ideas about God and the Nature of Everything. By having us to think about what it all means, we also think about whether it all hangs together. It doesn’t.

Scott still remains a top director, and there are sequences here that rank among the best he’s ever put together. A shameless use of Chekov’s gun sets up a body horror moment that combines grotesqueries with HR Giger’s creature design and a defiantly-feminist slant. Courage and awesome destruction define the inexorable climax. Yet there are big structural problems for every arresting standalone scene,  and the Alien semblance becomes a distraction. Important scenes hit the same beats as Scott’s 1979 classic, so where it matters most, Prometheus feels like a more handsome shadow of its inspiration.

Even without expectations that are borderline unfair, Prometheus is so damn frustrating. Lindlelof and Spaihts are unsure about their script, leaving enough wiggle room for a potential sequel. I should note Lindelof is the same guy whose twitter bio reads, “I’m one of the idiots behind Lost. And no, I don’t understand it either,” so his self-deprecation is hardly inspiring. For the production team and the cast (all of whom are convincingly competent), working on this movie must have been an act of faith. They trusted the writers and directors to create something coherent and brainy, a science fiction film that would rejuvenate a fledgling franchise. But when Raspace gravely intones, “We were so wrong,” I can’t help but wonder if she was talking to the guys behind the camera, too.