This scene is an example of how Lights Out plays with its monster. Rebecca sleeps next to a flashing tattoo sign that periodically floods her room with soft red light. That’s the entire mechanic of this scene — it’s on a timer. Also, it’s red. Photos courtesy Warner Bros.

Lights Out is a stellar horror film that walks the line between terrifying and fun, but before that, it’s a happy ending for a genius short.

After a pulse-pounding introduction in which a shadowy woman kills Paul (Billy Burke), Lights Out follows his step daughter, Rebecca (Teresa Palmer). Several years before, Rebecca’s mother and Paul’s widow, Sophie (Maria Bello) was left by her first husband and fell into a deep depression, in which she began communing with said shadow woman, the ghost of her old friend Diana (Alicia Vela-Bailey). Diana haunted Rebecca as a child, driving her to cut ties with her mother. Paul’s death exacerbates Sophie’s condition, and Diana once again begins stalking Rebecca and her young half-brother, Martin (Gabriel Bateman). Though content to simply run away from the situation when it was happening to her, Rebecca is determined to confront her mother and Diana and save Martin from a similar destiny.

This movie is, of course, based on the brilliant 2013 short film of the same name.

When you get fresh pants and watch it again, you notice a couple of things — despite the critical adulation, it’s actually a very traditional, by-the-numbers, sound-based jump scare sequence. You’ve seen this kind of thing a million times before, but it’s so perfectly executed that it doesn’t matter here.

Whenever you have a short like this, the hope is that it doesn’t get commercialized at all and the end result is essentially a 90-plus minute version of the short. That may sound like a matter of course, this is something that can go wrong.

Just last year we had Pixels, a soul-crushing example of what not to do. Sony grabbed the rights to this excellent, inventive 2010 short and then handed it to Adam Sandler and Chris Columbus, who had their own “creative” ideas, then stuffed it with product placement like Sony is wont to do. The end result was nothing like the short, but it ate the short up legally and practically — even if someone good gets the rights, it’ll be near impossible to adapt it again, because the feature, which became one of the most hated movies ever made, has name recognition.

With Lights Out, they’ve gotten it completely right. The short director, David F. Sandberg, was retained and makes his feature-length debut. James Wan attached his name for marketing purposes, but otherwise left the movie alone. The end result is very much an 81-minute version of the original short, dodging both the pitfalls that can beset adaptations and horror movies in general.

There are a lot of problems standard jump-scare movies face, and Lights Out gets around all of them. The key lies in Diana’s character design.

That’s all there is to her. Simple. Subtle. Uncanny. Brilliant.

The thing to understand is that most slasher movies key in on a monster that is clearly just a guy with a rubber mask. The classics are the ones that make this work, but a lot of movies can’t, and have to build themselves around disguising how terrible their villain looks. That’s the real reason it’s so rare for the monster to appear in a trailer — it’s not to build suspense, it’s because if you knew how bad it looked there’s no way you’d pay to see more. To disguise this in the movie itself, the monster never stays onscreen longer than a split second. On top of that, many are committed to a standard character structure where you’ve got at least one character present through the whole movie, so the monster can’t kill her. Combine all this and you get a 80-90 minute movie with only a handful of actual jump scenes which, for most of the runtime, asks you to fear a monster that can’t do any worse than jump out and say “boo” and sympathize with a lead that can’t do any better than keep on falling for it.

But by having a monster that can actually hold the screen, as well as one with a key trait that characters quickly pick up on, Lights Out opens up a world of possibilities for itself. The only thing that’s certain about Diana is that she vanishes when light is cast on her. It’s a weakness, but also a strength. She can hide in plain sight and jump out from the middle of the frame, and when she does, she’ll have more to do in the scene because her screentime isn’t limited to split seconds at a time. When Diana is out, she’s out for blood. The characters, in turn, have much more to do because there’s a practical way to banish her, and since she doesn’t go away once she gets a jump out of them, they have to. With the movie’s many extended jump scare sequences featuring this kind of actual interaction with the villain, it almost becomes an action movie.

And there are many, many extended jump scare sequences. Again, this movie doesn’t have to be shy with its monster, and it isn’t. Despite coming in at just 81 minutes, Lights Out feels satisfying because a good 30 percent of that time is spent with the monster out and about, wreaking havoc. Sandberg had a ton of ideas for what to do with this monster, and they all made their way into the movie. You get a lot of bang for your horror buck with this.

You’d think that this means the script penned by Eric Heisserer, who also produces, is the weakspot, and to an extent it is. Martin walks the line between being a likeable, genre-savvy character and an annoying little fart, and Rebecca’s clingy, selfish boyfriend, Bret (Alexander DiPersia), is the kind of mopey character you just want to leave the screen. I get the impression they were aiming high with the dialogue and trying to put in the nuance that comes with knowing people really well and being estranged from them, but it doesn’t come off at all, mostly because these two characters are so uneven. However, Sophie is played spectacularly, and the story as a whole coalesces into a frightening parable about depression and toxicity and ends up being another way Lights Out is a standard but superior horror film.

All the horror movies that really stick with people are about something more than the horror itself — the famous example is the original Nightmare on Elm Street, which is about the anxieties of growing up and having your first sexual encounters. Ghosts are typically representative of the psychological problems of whoever they haunt, and Diana is a doozy.

Sophie met Diana as a child when she was institutionalized for her depression, and Diana quickly latched onto her. Diana wouldn’t let anyone else near Sophie, and even hurt her when she began to get better. Diana was killed in a procedure to treat her skin condition, but her ghost returned with Sophie’s depression to haunt the people who cared about her and keep her all to herself. This relationship drives Sophie to become just as toxic and possessive with her children, and this in turn destabilizes Rebecca’s psyche.

Adding even more depth to their dynamic is Diana’s amorphous nature. Even in life, she was a malevolent, possessive user with a skin condition and heavily implied psychic powers. It’s never clear if she’s the cause of Sophie’s anguish, or a byproduct of it.

As anyone with experience with depression can tell you, this cycle of abuse is devastatingly real. Whether Diana is a literal toxic friend who just happens to be a ghost or the ghostly manifestation of Sophie’s unwellness, the things she might represent all say the same things. Just like abusive friends will slag you down so you don’t cut ties with them, depression sort of takes on a life of its own when you try to get better. It tells you you need it. It tells you not to take those pills, you’ll lose the parts of yourself you do like. It tells you your friends will abandon you, and you’ve got to get over on them first. Lights Out is one of the best explorations of these thoughts in recent media. It expands further into questions about at what point a person is beyond saving, and comes up with some complex answers. Though it seems like an accident, the movie’s themes run deep.

This feels like a classic. This feels like I’m talking about a movie that’s 30 years old and still talked about because it’s such a perfect example of everything the genre aspires to. If you like horror, you’ll love this one — see it.

Leopold Knopp is a formerly professional film critic, licensed massage therapist and journalism student at the University of North Texas. Like Reel Entropy on Facebook, follow it on Twitter @reelentropy, and shoot questions to reelentropy@gmail.com.