You think you’ve seen every way to dispatch a zombie, and then someone applies a chainsaw to a skull in a particularly satisfying manner.

But no matter how good that scene is, or the yards of entrails pulled out of bodies, scares are not the distinguishing feature of the Canadian filmmaker Jeff Barnaby’s new effort. Zombie stories are about the spread of lethal contamination, so Barnaby’s central premise is inspired: When dead people come back to ersatz life, it turns out that Indigenous folks are immune — a sardonic twist on their ancestors succumbing to diseases imported by the European settlers.

“Blood Quantum,” now streaming on Shudder, is set in 1981 in Red Crow, a fictional Mi’gmaq reserve that was also the setting of Barnaby’s debut, “Rhymes for Young Ghouls” (a grimly compelling drama available on Amazon Prime). The sheriff, Traylor (Michael Greyeyes), is appropriately stern and efficient, though he struggles to manage his dangerously hotheaded older son (Kiowa Gordon) — the young man goes by Lysol, which does not suggest a sunny personality.