Lights Out falls into that category of horror film that has a simple premise and an easy reveal: something evil lurks in the dark. The lights go on, it disappears. The lights go out and you're toast. It's hardly complex, but Lights Out is still unsetting and scary.

It's not a house that is the actual object of the haunting, it's a person (Maria Bello), a mentally fragile mother of two who is being haunted by a girl she befriended as a child and lost in an accident. The vindictive presence that's targeting her is more like the angry ghosts of Japanese folk tales, in that the family is being tormented by a spirit who is tied intimately to the family's dysfunctional history. It's a ghost who can exist -- and attack -- anywhere where there is darkness.

Refusing to release her demonic hold on her former playmate, the vengeful spirit attacks Bello's delicate, barely strung-together little clan, who ultimately fight back. Bello's daughter (Teresa Palmer) comes to her mother's rescue after her stepfather is killed and her little brother is apparently being stalked by the same entity.

There's real meat on the bones of the plot, which has interesting backstories and real world problems for its characters. Lights Out is not just the tale of disturbed entity descending vengefully upon a vulnerable family, it's a story that has a good emotional connection to the premise. The narrative relies as much on the emotional fragility of the characters as much as the tropes it employs with unnerving skill. In that respect, it's more like a psychological thriller with horror elements than a straightforward horror movie. The actors' performances are rock solid. Palmer is quite convincing in her role of frightened but determined daughter, with decent support from Bello and Gabriel Bateman as the younger brother.

There's also loads of tension and atmosphere, lots of creepy jumpscares and thrills that keep up until the very end. The technique of using darkness to its maximum effect is perfectly milked, creating the very believable illusion of something lurking around every corner, although director David F. Sandberg relies a bit too much on the single trope of walking verrryyy slowly through darkened rooms and hallways and down shadowy stairwells. This can be forgiven since the camera work is still pretty effective. Besides, it's not easy to think up brand new tricks.

Still, Sandberg does a terrific job building up the suspense, with some light relief at the right moments to make sure the movie doesn't take itself too seriously. He also gets to the main point quickly, without dragging out heavy moments or using hack plot points. The excellent cast and the relentless action will give you a great cinematic experience but the unique monster at the film's heart will have you sleeping with the lights on.