Stop me if you’ve heard this one before: A lantern-jawed jock, a vivacious blond bimbo, a bespectacled egghead, a wise-cracking stoner and a virginal goody-two-shoes go up to an isolated cabin in the woods for a lawless weekend of drugs, sex and rock ‘n’ roll. Instead, they end up getting picked off one-by-one by a horde of seemingly unkillable baddies.

Think you know the story? Think again.

Subverting the clichés and conventions of the horror genre with take-no-prisoners aplomb, “The Cabin in the Woods” blends the bare-bones story outlined above with a quirky, hilarious razor-wit. Then it introduces an unprecedented, self-aware, sci-fi conspiracy-theory concept that offers compelling explanations for damn near every overused plot device in the genre cinema playbook. A heady splash of epic, Lovecraft-inspired apocalyptic menace tops the whole thing off, for flavor.

Basically, without giving too much away, the core conceit goes like this: Imagine if almost every horror picture you ever saw took place in the same universe. “The Evil Dead.” “Hellraiser.” “The Strangers.” “Ringu.” They’re real, they happened and, what’s more, they’re happen again and again, over and over, in a dozen different permutations, all the time.

Now, imagine if there was a reason horny teenagers had to die at the hands of zombified rednecks, killer clowns and bloodthirsty mermen (yes, mermen). Imagine if there was a shadowy government organization controlling these events. Pocket protector-sporting paper-pushers turning on fog machines, unleashing the undead and convincing otherwise level-headed guys ‘n’ gals to have sex at the worst possible times or split up in the face of danger.

Groovy, no?

Thankfully, the movie never gets drunk on its own cleverness. It doesn’t smugly smack us over the head like the “Scream” or – ugh – “Scary Movie” franchises did. “The Cabin in the Woods” is more in the vein of postmodern slasher mockumentary “Behind the Mask: The Rise of Leslie Vernon.”

Though a divisive, excessively nihilistic climax derails things slightly at the very end, writer Joss Whedon and writer-director Drew Goddard once again prove their storytelling chops are just as legit as their fanboy street cred. In fact, they’ve crafted a mythos here that is so engaging, when it’s finally over, you wish you could go back in and delve deeper. It’s a rare movie that could actually benefit from being longer, but this is one of ‘em.

An existentialist, deconstructionist genre study that implicates the audience itself as both voyeur and villain, “The Cabin in the Woods” delivers all the raunch ‘n’ splatter we want when we’re watching a horror flick, but is smart and skillful enough to make us ask ourselves why.

4.5 stars out of 5