There is a lot of pretty niche comic book mythology swirling around “Madame Web,” the inspiration for the newest of Sony’s “Spider-Man” spinoffs.

This is a character who goes back to 1980 and whose powers of clairvoyance helped Peter Parker at some point. She’s elderly and blind and sits atop a web throne that keeps her alive. But to be honest, reading about her didn’t help give any more meaning or urgency to the Dakota Johnson movie that’s heading to theaters Wednesday. You’ve been warned.

“Madame Web” is striving to be a classic superhero setup movie, about how the future Madame Web — now just single gal paramedic Cassie Webb — comes to terms with her newfound power that allows her to see the future. Well, sometimes at least, when it involves a death or something extremely violent.

It’s also about the origins of a few other Spider-Women who are now just a couple of teenage girls, played by 20-somethings Julia Cornwall (Sydney Sweeney), Anya Corazon (Isabela Merced) and Celeste O’Connor (Mattie Franklin). Watching the flash-forwards to these three in their Spidey costumes makes you feel like there’s some Marvel TV show you forgot to watch that might make you care more.

A scene in which they try to sell the idea that all four women are connected in some cosmic way is so wildly strained (“you live in my building,” “you ran in front of my truck”) and inconsequential, you wonder if whichever screenwriter wrote their run-ins initially was even talking to the one who had to try to sell these coincidences. It’s impossible to know what exactly the four credited screenwriters (and three “story by” credits) are responsible for, but “Madame Web” feels like the stitched-together product of a bunch of people who weren’t actually collaborating.

There is also an alarming amount of repetition in just under two hours. Part of this is because Cassie is learning about her powers and sees various incidents play out over and over, which, by the fourth set piece, starts to get very tedious. You forgive it, a little, because Johnson is just always fun to watch and it at least serves a story purpose in theory. But then there’s all these scenes in which the bad guy, Ezekiel Sims (Tahar Rahim), is either seeing his future death at the hands of the Spider-Girls (or whatever we’re calling them) or barking at his associate (Zosia Mamet) to find them with her “Dark Knight”-era surveillance setup in his blandly cold penthouse.

We know Rahim to be a talented, charismatic actor, but Ezekiel is one of the dullest, most thinly sketched superhero villains in recent memory. The movie doesn’t even withhold his own cosmic connection to Cassie as a reveal — it literally opens with him killing her mother (Kerry Bishé) who is on a spider research trip in the Amazon while very pregnant with her. The venom, and some Amazonian spider-people, save the baby though.

Johnson’s singular performance style can make almost anything watchable. Her cool-girl deadpan is always interesting and funny and, thankfully, filmmaker S.J. Clarkson has the good sense to keep the camera on her as much as possible. She makes gems out of nothing and finds humor even while the script and story are crumbling around her. It’s too bad because there could have been a more fun movie in here — Clarkson imbues it with a distinctly feminine and teenage energy that makes good use of its soundtrack. But it spins itself into a knot trying to justify a silly story instead.

The studio, it seems, is playing a very long game with this one. Cassie’s paramedic colleague is Ben Parker (Adam Scott), whose sister-in-law Mary Parker (Emma Roberts) is about to give birth. But one has to imagine after seeing “Madame Web,” that, ironically, whatever payoff was planned may be a vision that will not come to pass.

“Madame Web,” a Sony Pictures release in theaters Feb. 14, is rated PG-13 by the Motion Picture Association for “violence/action and language.” Running time: 117 minutes. One and a half stars out of four.