“Antlers” (*1/2 out of four) was a flaccid horror thriller about a middle-school teacher (Keri Russell) and her brother (Jesse Plemons) whose a sherriff become embroiled with a mysterious student (Jeremy T. Thomas) who carries secrets that lead to terrifying encounters with an ancestral creature that threatens to end all their existence. Pale imitation of “Poltergeist” and also “The Sixth Sense” without much originality and with even lesser scares. Russell tries but is unable to enliven or enrich the proceedings; strong supporting actors Graham Greene, Amy Madigan, and Rory Cochrane are wasted in minor roles.