And what is happening in The Happening? It doesn't matter, but Andrew Eaton has some fantastic theories:
We know that M Night Shyamalan is fond of twists. Perhaps he invented the whole story about him writing a script called The Green Effect then changing the title to The Happening as a red herring. Perhaps we are just meant to think this is an environmentally themed movie. We know Mark Wahlberg and Zooey Deschanel's characters are an estranged couple. Is Mark so desperate to win Zooey back that he pretends there's a national crisis, just so he can persuade her to come out to his farmhouse so they can patch things up? In a surprise twist, it turns out that there is a national crisis, but Zooey doesn't believe him! The Happening is, in fact, a hilarious caper comedy.
The Happening actually makes no sense whatsoever, like Lost. People start dying for no reason, nobody ever finds out why, Mark Wahlberg and Zooey Deschanel wander around the countryside for a while, where the forest makes mysterious noises, a polar bear turns up, and they find a hatch which, they eventually discover, contains a very old computer with a number ticking down to zero. But this turns out to be a minor plot detail. At the end we discover it was all a dream, or something. It's, y'know, postmodern.