Twelve years ago, Paranormal Activity was the low-budget, do-it-yourself horror film success story of 2007: Made for a paltry $15,000 or so, it found a receptive audience and grossed $193 million worldwide.  Based on the return of investment (Paramount/DreamWorks acquired the film rights for $350,000), it is allegedly the most profitable film in the history of film.  The movie spawned 5 sequels (technically six, if you count the 100% authorized Japanese release Paranormal Activity 2: Tokyo Night), with the most recent, 2015’s Paranormal Activity: The Ghost Dimension said to be the final chapter in the series.

But it all began with the original.  Paranormal Activity being a horror movie, the plot is fairly straightforward and standard: a twenty-something couple, Micah and Katie, live in relative quiet and happiness until Micah brings home a video camera to document the strange occurrences that happen during the night. Katie reveals that she has been haunted since childhood, and hires a psychic to investigate. The psychic, like every other psychic who’s ever existed or ever will exist, provides no help at all except to advise the couple to call a demonologist and not try to confront the monster themselves.

You can guess what happens next: they ignore the psychic’s advice, Micah invites the demon to do its worst, and over the course of the next couple weeks, it does. Maybe that’s a spoiler, but we’re talking about a horror movie here. They’re not going to agree to a truce and all go out for frosty chocolate milkshakes.

While being praised by some, the climax of the film angered a lot of viewers. Really, there’s only so long viewers can be expected to watch a person taunt a mysterious, possibly supernatural entity that’s clearly mean-spirited if not outright hostile. On the other hand, we don’t go to movies to watch smart people doing smart things—if I wanted that, I’d hire a documentary crew to follow me around all day, hi-yo! What brings us to horror movies is the scares, and Paranormal Activity serves up some genuinely creepy stuff alongside old horror standbys like Ouija boards and quick jumps.

If it wasn’t clear from the above plot description, Micah spends pretty much the entire movie being a jackass. Not that this in and of itself is strange, like there aren’t jackasses in the world, of course, but he maintains his obnoxiousness so long that by the end, I was cheering for the monster. I’m guessing that’s not what the filmmakers wanted. Story-wise, his skepticism is really only there to keep the pair in the house so more scary stuff can happen—the filmmakers didn’t do anything to earn his wild and inconsistent swings between skepticism and credulity. Katie is a complete blank slate—even though she’s more affected by the, uh, paranormal activity and spends more time on screen than Micah, we don’t really learn a lot about her or get much reason to care what happens to her. There are your protagonists, folks: Annoying and Boring.

For a story based on things that don’t actually exist, however, most of the movie actually does a good job of making things seem real. The incidental, unexplained bumps in the night are relatable and draw the audience in, setting us up for the supernatural stuff later. Unfortunately, like so many horror movies, the, uh, paranormal activity loses its effect once we know exactly what’s going on. And even though it looks like the movie violates the old storytelling rule of “show, don’t tell,” it turns out to be a good decision -I’d much rather be told the explanation than see a cheesy, low-budget rubber suit.

The filmmakers clearly subscribed to the idea that the unknown is scarier than anything that’s known, so we the audience never actually see what’s terrorizing our plucky-if-slightly-really-stupid couple. The “found footage” approach works to great effect in the early scenes – we see what happens before the characters do, leading to some truly great “LOOK OUT!” moments as Micah finds out what his girlfriend is doing while he’s sleeping. The effect stays around until the endgame, once the audience has been beaten about the head with the obvious explanation for everything. Still, as the credits rolled, my wife and I had to make a pact to never interfere with each other’s sleep. That’s relatable horror, folks!

All in all, Paranormal Activity didn’t exactly break the mold when it came out – but it certainly was a relatively fresh take in a horror genre that’s been bloated with the same old stuff for quite some time.  It’s no wonder that the movie captivated audiences and created a half-dozen films in its series.