Imagine a horror movie where the monster looks into people's minds and takes the shape of beings it sees there to "blend in" or take the appearance of something that might discourage prey from running or threats from attacking, as it's natural form is incredibly vulnerable, with highly elastic but thin skin and no solid bones to protect its organs, as well as limited vision. Then it hides out in a psychiatric hospital, where it manages to move about and hunt with ease, and the movie follows a highly schizophrenic resident who happened to see it kill another patient in it's real form, and now has to find a way to defeat or escape it on their own- because who would believe them?- while also being unable to tell whether any of the things they hallucinate are the creature in disguise.
