It Follows (2015)
When carefree teenager Jay sleeps with her older boyfriend for the first time, she learns that she is the latest recipient of a fatal curse that is passed from victim to victim via sexual intercourse. Death, Jay learns, will creep inexorably toward her as either a friend or a stranger. Jay's friends don't believe her seemingly paranoid ravings, until they too begin to see the phantom assassins and band together to help her defend herself.
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