LET'S SEE how easy it is to talk you out of seeing A Field in England. First of all, it's in black and white. Second, it takes place in the 17th century, and all the characters speak in impenetrable dialect while being covered in varying degrees of filth and shit. Finally, it's a self-consciously arty, virtually plotless exercise that's capped by a bug-nuts trip-out sequence in which one of the characters shovels handfuls of psilocybin mushrooms into his mouth like they're Girl Scout Cookies.

Now let me try something harder: persuading you that A Field in England—the fourth feature from English director Ben Wheatley (Kill List, Sightseers)—is not merely worthwhile, it's among the most challenging and astonishing pieces of cinema around, transcending any "drug movie" clichés in favor of something fascinating, terrifying, and unique.

Whitehead (Reece Shearsmith) is in the employ of an astrologer-like mystic, and he's been tasked with locating O'Neil (Michael Smiley), who's stolen some vital documents from his master. At the edge of a battlefield, Whitehead encounters two soldiers (Peter Ferdinando and Richard Glover); a third soldier, Cutler (Ryan Pope), tells them of a nearby alehouse. On their march to get drunk, Cutler drugs them with some mushroom soup, and takes them to O'Neil, who's become a sort of evil warlock, using his powers to force them to dig for treasure.

Actually, Cutler doesn't bring them to O'Neil so much as have them pull him into existence with a rope—one of many inexplicable things that happens in A Field in England. There are all kinds of arcane references to superstitions and beliefs of the period, when magic and alchemy were stubbornly, violently giving way to science. ("Modernity is just this wafer-thin thing teetering on top of ancient things," said Wheatley in a recent interview with Bloody Disgusting.) Wheatley's films explore, to varying degrees of horror, the razor's edge where civilized humans turn into murderous savages, and O'Neil is one of his most horrifying characters yet. Wheatley's climactic psychedelic sequence is an absolute tour de force—while getting to that part can be tough going, it's positively worth the effort.