If you’ve ever seen a M. Night Shyamalan film, you know what’s happening; eerie shit goes down, death looms, no one knows why — and it happens in the middle of a Pennsylvania cornfield. The Village and Signs rolled that way. Here, the scourge du jour is a neurotoxin that puts everyone in a suicidal stupor. (The grim acts of offing earned Shyamalan his “first” R rating — as the ads boast.) Is it a terrorist attack, a government experiment run amok, or just nature giving us a little payback for screwing up the planet? Shyamalan stretches this enigma beyond credibility. Despite that and some tiresome over-explanation, the film almost makes sense in the end. Mark Wahlberg and Zooey Deschanel serve as the director’s microcosmic lens to the mass hysteria. They’re a troubled couple, but the real trouble is behind the lens — what’s happening is that Shyamalan has lost his sixth sense. 91 Minutes | Boston Common + Fenway + Somerville Theatre + Chestnut Hill + Embassy + Suburbs