Eddie Murphy famously asked, “Why don’t white people leave the house when there’s a ghost?” It’s a testament to director David Jung’s smart script and Shane Johnson’s performance that Michael King’s decisions seem largely free of horror-movie logic — the stubborn refusal to acknowledge danger, an insistence on going it alone. Lost in grief, the widowed documentarian King throws himself into an exploration of black magic, wanting to prove that all spirituality is bunk. Johnson tilts at this windmill with conviction, underplaying the desperation that such tilting reveals. King’s tour of unsavory mystics includes a dying priest confessing that exorcisms are real, a funeral director who practices necromancy, and a Satanist couple, more sleazy than spooky. But when he begins behaving strangely after one of these encounters, King doesn’t retreat; he investigates … intelligently. He goes to a psychiatrist; he has his audio recordings analyzed. He’s as curious as we are, and the film is more engaging because of it. Alas, after a promising start, rote possession imagery eventually becomes the focus, culminating in a by-the-numbers ending. But even then, the film offers some new shudders — King’s demonic guest has an affinity for ants, and Jung uses them to unsettling effect.