Director David Schwimmer (yes, that one) does something very distinctive in this film, enabling a sense of danger and menace about what we know is coming (but hope it isn't) and which we know Annie (played very bravely by an actress of Liana Liberato's age at the time) is too immature to see coming. It doesn't shy away from the hideous reality of what happens to her but it somehow makes it watchable – at times even pedestrian.

There's nothing upsetting enough to make you turn it off, but there's a palpable sense of hope Annie will be too smart to fall for the evil stalking her. Because it's not about hockey mask-wearing serial killers or monsters from the deep, it's something both much more everyday and much more horrifying.

Annie is an archetypal suburban teenager – pretty, sporty, full of vitality, plugged into her friends via technology and on the cusp of womanhood. Her liberal parents Will (Clive Owen) and Lynn (Catherine Keener) are supportive and understanding, but they can't stop monsters all too ready to prey on Annie's vulnerability. Maybe the scary moral of the story is that we can't really protect our kids from harm, we can only be there to help them survive it.

One such harm is a guy we later learn is a high school physics teacher (in a final coda that will only make you angry). We have as little idea who he really is as Annie does at first, but he's posing as a high school kid she starts flirting with online – telling her what she wants to hear as she tries to grow into her body and soul, wondering if she's pretty enough, cool enough and everything else teenagers go through.

By the time Annie arranges to meet him in a shopping mall (with you urging her to log out, hang up or run away at every step) and he turns out to be a man her father's age, Annie's disgusted and ready to leave, but he's too smart for her. He uses a polished routine to hook her in, and soon he has Annie – frightened but trying to be cool – in a motel room posing in underwear for him.

The fallout comes soon after when the cops come to pick Annie up from school, setting tongues wagging everywhere and setting her father on a warpath. The family starts working with an FBI agent (Clarke) who's targeting the guy and others like him, but Will has such a hard time accepting what's happened his rage threatens to tear him away from Annie when she needs him most, even if she doesn't know it.

While Will and the FBI butt heads over finding the guy so Will can disembowel him, Annie's only outlet comes from a psychologist (Viola Davis) who becomes her only hope for understanding what she's been through.

You want the cops to catch the guy and you want to see Will (or anyone) cave his head in with a fire extinguisher, much like we saw in Irreversible, and I'm not going to say whether that happens, because as frustrating as the resolution of that part of the story may or may not be, the movie's not about that. It's about how Annie has to be able to trust her father and feel like he's protecting and loving her rather than losing him to his desire for revenge.

There are rough patches in both the performance and the plot. At times it seems the script is juggling too many elements to really service them all, but as a kind of modern day Public Service Announcement it's very effective. And also – perhaps not even intentionally – it's a skin-crawling experience without a single drop of blood, drawn weapon or an overt sense of danger.

It's the horror of banality and the banality of evil, and Liberato's frightened, flashing eyes will stay with you for a long time.