‘Barbarian’ messes about ingeniously with horror film tropes

“Barbarian” starts at night with a heavy downpour and a thunderclap. So far, so good, for what seems to be a classic horror movie. Hold onto your ponchos.

Some two hours later you will have seen virtually every horror convention — from doors slamming on their own to weird monsters with mommy issues and subterranean torture rooms — ingeniously messed with. Even the title is a misdirection.

“Barbarian” marks the auspicious feature film debut of director-writer Zach Cregger, someone well-versed in film tropes and with a subtle skill at social satire approaching Jordan Peele levels. He will also somehow make you laugh hard in oases of humor before the dread reappears.

It starts on a rainy middle-of-the-night street of a half-ruined section of Detroit when a young woman (Georgina Campbell) finds her Airbnb-rented house weirdly occupied by a stranger (Bill Skarsgård.) “I don’t know what the protocol for all this is,” he tells her. Their little awkward dance — checking booking receipts, offering to sleep on the couch — seems to point to a tiny tale of gender roles and microaggressions. Yet somehow it will evolve into a hair-on-fire horror flick with eyeball-gouged skulls.

Make no mistake: Cregger is playing with us every step of the way. Casting Skarsgård as the is-he-a-sweetie-or-not comes colored by his role as Pennywise in “It,” and even the film’s setting is a sleight of hand — a bombed-out section of Detroit with the Airbnb home in its center was actually filmed in Bulgaria.

Later, the arrival of Justin Long — playing a slimy TV figure from a new show tellingly called “Chip Off the Block” — clouds things further, his being an actor long associated with good-guy comedy. Cregger is somehow leaning into Hollywood conventions even outside his own movie.

As good as the casting is, it is the house that is the real star, nicely appointed but cookie-cutter, in a sea of torn-up and decaying homes. It has an alarming basement with a horrific room that has a soiled bed, a bucket and a camera. But there’s more: An even creepier cavernous space below. You can almost hear Cregger cackling as our heroes face TWO horror-ready basements. “You’re safe,” says one. “I don’t think I am,” another replies. (They’re not, by the way, of course.)

Campbell spends so much time trying to escape the house and yet smashing her way back into it moments later that more than one person in the audience at a recent screening loudly implored her to get into her Jeep Cherokee and just drive away.

All along are reaches for real social issues — redlining, misogyny, character redemption, gun accidents and police misconduct, among them — that elevate the film from genre-gazing silliness. There may be a monster inside the house, but forces outside that structure keep that monster firmly inside.

“Barbarian” is firmly of its time — online house rental bookings, smart-phone flashlights and real estate square footage listings — and yet timeless, like an arm ripped off and used as a club. It was predictable and yet impossible to predict. It’s worth booking one night soon.