Scary is subjective, what makes one person quiver down to the base of their spine makes the person sitting next to them yawn with boredom, all that good stuff, and I wasn't thinking about any of that "let us be sensibly objective" bullshit while I was quivering in pleasurable agony in the mostly dark theater watching Lights Out, a horror film that jangled every last one of my nerves more expertly than anything in ages. Since at least The Babadook, and even that at least let up now and then; Lights Out succeeded in continuously freaking my shit out right up till the very end. Even after it had fully laid out all the exposition clarifying what was going on - especially after that point, in fact - which virtually always the death knell of cinematic ghost stories.

Setting that aside, is this, in fact, a good movie? Well, that depends on what you consider "good" to mean. Having compared it to The Babadook, I might as well keep on doing it: like that film, Lights Out is a symbolic study of depression, specifically how a woman whose husband has recently died begins to fall apart, leaving her young son to deal with the emotional fallout, which comes in the form of a long-fingered, rasping ghost that flutters around at the edges of the light. And Lights Out is... not really great at doing most of that. In fairness, it's not really trying: at no point in that little sketch did I actually get as far as the film's actual protagonist, the woman's adult daughter by a previous marriage, and calling Lights Out a symbolic study of anything is already loading it up with baggage it wasn't built to carry. This isn't a "smart" movie. It is a "scare the bejesus out of you" movie.

The hook is absurdly straightforward: when the light is off, it is possible to see crouching in doorways or in the backs of rooms the figure of a spindly humanoid with long scraggly hair. When the light is on, that figure disappears - but it can move. And when you turn the light back off, it can attack with those awful talon-like figures. If that sounds familiar, that's because there's nothing inherently unique about this conceit: if nothing else, Lights Out bears clear similarities to "Blink", among the best-loved episodes of the 21st Century incarnation of Doctor Who, and I shouldn't think that it was invented there, either. So what, if it's well-executed, and director David F. Sandberg already proved himself capable of that back in 2013, when he used this same idea for a punishing little short - also titled Lights Out - that earned him the chance to expand it into this feature, with the assistance of writer Eric Heisserer (the curious can find the short online without too much effort - right here, for example - and if you're not curious you really ought to be).

The feature-length Lights Out is not as good as 80 minutes of the 2.5 minute Lights Out, since at that length it's obliged to trot out character drama, and the drama it comes up with isn't the best in the world. So we've got Rebecca (Teresa Palmer), about whose current life we learn very little other than that there's a guy, Bret (Alexander DiPersia), who's over-the-moon crazy for her, but she wants very much to keep things at "we hang out and have sex" level, even after eight months. This, we can infer, is because of the broken family life she left behind: her mother, Sophie (Maria Bello) has frequent bouts of crippling depression, which was apparently enough to drive Rebecca's dad away many years ago. Since then, Sophie has remarried and had a son, Martin (Gabriel Bateman), who is about ten now, and by all accounts she's been able to get things more or less under control. But all it takes is a nasty setback to put her back in a depressive spiral, and they don't come much nastier than losing your husband to a brutal attack by an unidentified assailant. We know who killed poor Paul (Billy Burke), though - it was that scraggly human figure (Alicia Vela-Bailey) skulking around in the warehouse he managed late one night.

The plot develops pretty seamlessly from this: the thing shows up in Martin's bedroom at night, and Sophie apparently knows it and talks to it like a friend, which is when Rebecca forces herself back into a situation she thought was far behind her. The secrets of what link the creature has to Sophie's childhood are explained with gratifyingly little fuss: unlike the vast majority of ghost movies I can name, Lights Out doesn't present the "aha, this is the photograph and these are the news reports that let us know this wrathful spirit's identity!" as the kick-off to the disappointing third act pseudo-exorcism, we learn exactly what's up with "Diana", as the thing calls itself, scratching its name into Rebecca's floor, before the halfway point of the movie. I find this enormously gratifying: it makes Diana somehow much more threatening and horrible, in that knowing almost everything there is to know about her does not in any way make Rebecca and Martin safer. Knowing everything just underscores how difficult it is to escape her, since there will always be shadowy places that she can hide.

It's a beautiful piece of machinery: Sandberg uses lots of empty frames with hanging corners drooping with gloomy shadows to keep us on our toes: there's always a place for Diana to suddenly swoop in to terrorise the characters, so it grows more and more nerve-wracking as we keep waiting for jump scares that don't pay off. Director of photography Marc Spicer has a field day with all the underlit interiors he's asked to supply (it's a pretty satisfactory knock-off of Gordon Willis's work), and goes all-in on the finale, lit with what is clearly not an actual blacklight, but has the sickly, nauseating colors that imply something akin to one. And the editing, by Michel Aller and Kirk M. Morri, is superb: given how much the film's very concept rests on alternating between what you see and what you don't, the precision of deciding where the camera is pointing at any given beat is vital to keeping up the sense of constant wariness that drives the movie.

The pity about all this is that it can't be tied to a better human story: I'm not inherently opposed to the depression narrative, which gives Lights Out something of the feeling of an early-season episode of The X-Files, in which the paranormal gives weight to character drama and vice-versa. But these particular characters - more to the point, these particular performances - don't live up to that. Bello is dismayingly broad in her portrayal, while Palmer's early prickly defensiveness which she only lets down by accident (her flirtation scenes with DePersia are excellent, though he is kind of terrible at everything else) grows less impressive as it becomes clear that she's not going to try to do much of anything else. Bateman is largely wonderful at playing a child who has to play-act at being a grown-up because the actual grown-ups are letting him down, but doesn't quite get how to do it, and the film needs a strong performance in his lynchpin role; but there's not much else going around as far as the acting is concerned. Perhaps with a stronger human element, we'd be looking at an instant horror classic: as it is, I shall content myself with being contented by getting a good strong dose of the creeps, always a rare pleasure for the horror film habitué.