Spoilers coming. Not that it matters all that much. If you've seen the backwards-motion trailer you've already got this one figured out. Anyway, you've been warned.
Bad, predictable horror films can teach you lessons. Here are some:
Ironic detachment will not save you from scary movie cliché. It will do you teens no good to move into the house next to the house at the end of the street where a brutal child-on-parents homicide went down, announce to your mother, "This must be the Mr. and Mrs. Dead People house," and then go on your merry way thinking that you're too cool to be scared of that sort of thing. Flippant attitudes like that will only lead to you feeling like you're totally safe from harm on the dark night you finally decide to investigate, alone, that very same cursed home, making your way to the basement and then through the trap door to the second sub-basement and then through the mysteriously locked door at the end of the Caligari-like horror hallway.
Furthermore, always listen to your parents because everything they say is true and right. Not since the Tori Spelling TV movie Mother, May I Sleep With Danger has a concerned mom (Elizabeth Shue, Oscar nominee, too good for everything here and she knows it) doled out such fervent, nearly clairvoyant warnings to her daughter (Jennifer Lawrence, Oscar nominee, paying some sort of young actor dues) about the creepy feeling she has about that house and its lone inhabitant, Mr. and Mrs. Dead People's orphaned son (Max Thieriot). The kid's brain-damaged sister bludgeoned Mom and Dad to death and then fled into the woods, never to be seen again. Now he lives reclusively, flipping lights on and off in the middle of the night and tending to something that lives behind the door at the end of the hall in that extra basement.
Oh, wait, you know what? Scratch that rule. Sometimes your parents are former sluts or current crackheads and doling out relentless abuse. Then you should not listen to them at all. Maybe you should even try to murder them. Look, just use your best idiot judgment and go do your thing. Walk alone on dark roads at night without concern for your well-being and poke around crime scenes in the dark. What's the worst that could happen?
Also, please remember to be completely reactionary when it comes to people who do things you don't understand. Because if a person makes you feel all ooky inside -- let's just call him the nice neighbor boy you really want to make out with but who everyone else thinks is tainted from the way his parents were murdered and because of how his sister is now a woods-monster -- then that gnawing discomfort in your gut is probably not your fault. That person is almost certainly deserving of the community's distrust and abuse, pretty much guaranteed to be mentally unbalanced and/or a secret killer, already spying on you from the woods, waiting for a chance to turn your life into a living hell of kidnapping and torture
And never lie to your mom, your dumb friends or the local sheriff (Gil Bellows) as to your whereabouts. Because you're going to be chloroformed and locked in the trunk of a car. And one lone person in a packed movie theater will begin slowly applauding your fate, cracking up the rest of the audience, turning them all against you. Is that what you want?