Whenever a film, regardless of genre, opens with a title card claiming it’s “based on a true story” or “based on true events,” moviegoers generally know to bring a certain level of skepticism to the proceedings. The “based on…” line may give a particular film a sheen of verisimilitude that, at least when the shocks and scares are occupying the screen, intensify them, but no one should expect anything approaching a fundamental truth or truths about the subject, especially when the subject in question, demonic possession, and thus, the film centered on the subject, The Possession, remains one mired in religious superstition and not in verifiable fact. In short, don’t believe what you see or here, except whatever causes you to jump out of your seat or curl up in your chair, half-hidden under your coat, jacket, or blanket.