The governess is thoroughly ungoverned in “Victorian Psycho,” a grisly ostensible horror comedy from director Zachary Wigon that’s neither frightening nor funny enough to pass muster — and not quite outrageous enough to garner the kind of notoriety it’s aiming for, either. A shot of lurid genre energy that at least provided some tonal contrast at the tail end of a generally tasteful Un Certain Regard program in Cannes, the film stars a miscast Maika Monroe as an unhinged young woman hired by a wealthy family in rural 19th-century England to raise and educate their young son (and daughter, they add grudgingly). It doesn’t take long to discover she’s pretty much the anti-Mary Poppins, or maybe just the antichrist — likelier to recommend a spoonful of cyanide to make the medicine go down.

There’s promise in the idea of a prim, well-spoken but forever subjugated nanny wreaking bloody revenge on England’s cruelly non-negotiable class system. But “Victorian Psycho,” adapted by Spanish author Virginia Feito from her own novel, never commits to the idea — or any idea, really — as it shows its hand early and gets straight down to the business of lavish and fairly undiscriminating bloodshed. From the get-go, there’s scarcely any mystery about who Monroe’s kill-happy carer Winifred Notty is, and with little countering interest in why she is, the film isn’t left with much to do but cheer her on as she terrorizes her masters, her charges and her colleagues alike, at the glum Gothic mansion cursed with her presence.

It’s hard to determine exactly what Cannes selectors thought they had when they slotted former film critic Wigon’s third feature in their second-most prestigious tier: Perhaps they identified more punk spirit in its prankishness than is strictly there, or were extending the benefit of the doubt from his more impressively controlled 2022 thriller “Sanctuary.” Either way, with the luster of the festival premiere likely to have worn off by the time Bleecker Street releases the film in late September, the film hasn’t much arthouse crossover potential — and while genre heads may appreciate some of the gore, the accompanying goofy quippery won’t be for all of them either. If it’s to find a following, it will likely be on VOD.

Though she’s sought to expand her repertoire with recent vehicles like the Colleen Hoover adaptation “Reminders of Him” and the feminist fairytale “100 Nights of Hero,” Maika Monroe remains best known as the premier millennial scream queen. It’s a reputation to which “Victorian Psycho” acts as a pointed rejoinder: This time she’s the one causing all the screaming. From the moment we encounter Winifred in the back of a carriage bound for the forbidding Ensor House on the Yorkshire moors, there’s something immediately off about her — and it’s not just Monroe’s peculiar RP accent, though that doesn’t help. The actor’s twitchy body language, in conjunction with DP Nico Aguilar’s queasy deployment of wide-angle lenses, clue us into the character’s extreme unwellness even before, on being shown to her quarters, she spots a severed ear on the floor (whose? how? why?) and gobbles it right up.

If Winifred is instantly, bizarrely offputting, her employers are more straightforwardly ghastly. As posh imbeciles John and Emily Pounds, Jason Isaacs and Ruth Wilson are directed toward full-tilt caricature to make our antiheroine look a little more human by comparison — it doesn’t really work, but the two British pros do serve up the most amusing line readings and reaction shots here. The film’s best performances, however, come from the youngsters playing Winifred’s new wards. Jacobi Jupe (“Hamnet”) brings just the right blend of bratty entitlement and vulnerable naïveté to the unfairly favored elder son Andrew, while as his perpetually disregarded sister Drusilla (“She’s at an age where fertility can be ravaged by over-education,” decrees her father), Evie Templeton does a subtler job than Monroe of hinting at some innate evil, perhaps equivalent to whatever demon has consumed her new governess.

Winifred calls said demon Fred, by the way, and he/she/it gets to work early, first bloodily dispatching a lecherous gardener who threatens to reveal her secret. A tentative friendship with nervous nursemaid Miss Lamb (Thomasin McKenzie, given little to do) ends quickly and brutally, before Wini/Fred set their sights higher. It’s part of the joke that she’s more or less hiding in plain sight as bodies unaccountably vanish around her — while she candidly lists the various untimely deaths and disappearances that have befallen previous children under her care — but it wears thin pretty quickly, as we merely wait for the inevitable climactic carnage, with not much secondary plotting to fill the time.

That perverse absence of tension wastes any baleful atmosphere built up by Aguilar’s off-kilter lensing, Ariel Marx’s loudly grumbling score or, most impressively, Jeremy Reed’s ashy, expensively rotting production design, with its mixture of plush Victorian grandeur and cartoon gothic embellishments. “Victorian Psycho” isn’t just all dressed up with nowhere to go, but equally aimless when it loses its composure: Losing your mind and surrendering to the darkness, in the movies at least, should be more fun than this.