Sometimes movies fail when all the right pieces are in place but the final product just doesn’t come together. And then there are times when either the concept or structure of the story couldn’t possibly have worked, which dooms the film from the start. Insidious: Chapter 3 never had a chance.

In terms of narrative structure, it’s a nightmare, a story so poorly told it’s shocking the script was green-lit. Writer/director Leigh Whannell co-wrote and starred (as Specs) in the first two Insidious films (which were directed by James Wan, who passed on this project due to his Furious 7 commitments), so clearly Whannell is familiar with what a good script should look like as production begins. How we wound up with such a disjointed and ineptly wrought story only Whannell knows, but it’s disappointing.

Chapter 3 is a prequel to Insidious (2010) and its 2013 sequel, so it’s a bit inexplicable that you need to have seen at least the first movie to understand what’s happening here. What you need to know is that “the Further” is another dimension in which the souls of dead people lurk with the hope of attaching to a living person. When the demons do glom onto the living, horrible things happen. Time for the exorcism. Elise (Lin Shaye), the psychic who helped others travel into the Further in the first two films, is one of the few who can help expel the demons.

Chapter 3 doesn’t give us Elise’s origin story; instead, it tells of a case she worked shortly before helping the Lambert family in the first movie. After teenager Quinn (Stefanie Scott) comes to Elise in the opening scene, asking to communicate with Quinn’s recently deceased mother, Elise tells her she can’t help her and to not try to contact her mother, with foreboding words of warning: “If you call out to one of the dead,” Elise says, “all of them can hear you.”

So of course in the very next scene, Quinn is trying to channel Mom. (Kids today just don’t listen.)

She doesn’t reach her mother, but she does get a pesky demon on her tail. And for the next 45 minutes, the hellish imp messes with her head, throws her out of bed, knocks on walls, rings bells, tries to pull her out a fourth-story window — you know, the usual satanic shenanigans. It’s unclear why the demon would come and go instead of just taking over her body, but I think that’s one of those logical questions you’re not supposed to ask about horror movies.

After these tediously repetitive instances of the demon toying with Quinn and her poor father Sean (Dermot Mulroney) struggling to take care of her, Elise agrees to help. A full 15 minutes later, they get together and try to attack the demon, now with the help of paranormal investigators Specs (Whannell) and Tucker (Angus Sampson). So yes, it takes a full hour of the 97-minute running time for the main action to begin. This is what I mean by “structural nightmare.” See, usually, the main action/conflict comes roughly 30 minutes into the movie and thrusts the story forward, leading to a second conflict at the 60-minute point that leads to the conclusion. This allows suspense to build gradually and culminate in the climax. By having only one conflict of note, Chapter 3 draws out what little suspense it has until it’s just tiresome and, even then, the movie isn’t over.

This would be more forgivable if the scares were decent, but nothing is scary when it’s repetitive and predictable. Anyone who’s seen a horror movie — let alone the Insidious franchise — knows these tricks: Demon shockingly appears in the distance, behind the curtain, in the doorway, on top of the heroine, leaves bloody footprints behind, etc. Thus, though the sound and production design are solid, the narrative and so-called frightening moments are too underwhelming to be effective.

It’s also worth asking: Why a prequel? Why not continue moving the Insidious story forward rather than put it in reverse to reveal inconsequential info that predates the first two films? There’s nothing here that we absolutely had to know that sheds clearer light on what we’ve already seen. All of Insidious: Chapter 3 feels like unnecessary filler, and there’s a place prequels are supposed to go when they’re this pointless: Straight to DVD hell.