It Follows (2015)

Girl sleeps with boy and then is informed that, until she has sex with someone in order to pass it along, she’s cursed. The curse comes in the form of an identity-shifting and silent “person” who simply trudges determinedly toward her. Should the walker get to her, it will kill her.

And that’s pretty much all there is to this, but it really works. No need to fancy up such a simple and terrifying concept.

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