Malignant is the kind of movie you breathlessly tell everybody and their neighbor about — not because it’s high art, but because it just must be seen to be believed.

Writer-director James Wan, co-creator of the Saw franchise, returns to the genre that made him. Here, he delivers a film so shocking that it was held back from reviews until the day of the release in order to save its trap door of a third act from being spoiled by the masses. Usually, a movie being held that late means it’s a disaster. In Malignant’s case, it makes a splendid argument for going into a film fresh — the alternative would be rotten indeed.

Wan’s film is an extreme lunge away from the recent trend of “elevated horror,” a term that mistakenly situates brilliant movies like Jordan Peele’s Get Out and Jennifer Kent’s The Babadook outside the norm. But horror has been historically steeped in sociopolitical themes. Peele and Kent are descendants of a proud tradition of horror as conduit for social commentary. Heck, you can go back to Mary Shelley and Edgar Allen Poe to find smart, socially conscious horror stories. Malignant, however, is part of another proud tradition, finding much more in common with those trashy fake trailers you might’ve seen on the Quentin Tarantino/Robert Rodriguez smashup Grindhouse of the mid-Aughts.

To find theme in Malignant, you must delight in hyperbole, in those scratchy trailer voices that heralded the coming of new exploitation movies. “Malignant is ... terror! Malignant is ... blood! Malignant is ... watching you!" Cue a freeze-frame over a red celluloid face screaming in terror. It’s a sleek homage to the Giallo past and a startling addition to the event-horror present.

Already the victim of an abusive partner, Madison (Annabelle Wallis, in a perpetual state of shock) now finds herself on the receiving end of horrid, blood-soaked visions of murder that are playing out in real life. The first two-thirds of the film click by with somewhat predictable tropes — a rundown psychiatric hospital, a long-haired mystery man hacking people to bits, cops doing cop things. But a third-act twist will make you long for a packed midnight screening, where viewers hoot and holler as their minds are melted by the sincere insanity of Wan’s vision. It’s part Argento, part early Peter Jackson splatterfest, part Minority Report. Malignant is mightily stupid, but in the most satisfying, hair-raising way. You’ll never look at a trench coat the same way again.

Wan rewards the patient with an ending to remember, the kind of hilariously gory disaster meltdown where everyone in the film instantly becomes victim to realization and the crockpot explodes and burns the house down. Wallis’ look of befuddlement throughout the film is apt — this is a crazy-ass movie, the kind of shameless passion project afforded to directors like Wan who are making billions of dollars for studios with other, more mainstream projects.

This one might not be for everyone (don’t go on a date or eat a full meal before you see this), but for those of us who still enjoy being knocked out of our chairs by something wacky, distasteful and beguilingly fun, Malignant is ... just about perfect.