I can't tell you that. In fact, don't let anyone spoil the reason why people are committing suicide en masse in the movie. It's not a surprise-twist kind of thing: It's just that you'll never be able to take the film seriously if you know the answer going in.
I can tell you that a lot of people are going to hate M. Night Shyamalan's The Happening when it opens on Friday. The movie is going to divide audiences, with the cons outnumbering the pros. But the pros will definitely be there - me among them.
If it's not quite on par with Signs or The Sixth Sense, The Happening is definitely a bounce back from the turgidness of The Village and the idiocy of Lady in the Water. Even when his scripts aren't working, Shyamalan knows how to frame shots and build suspense like a fiend: This is a taut, lean (90 minutes), beautifully directed movie built around a premise that no filmmaker could have pulled off successfully.
But the performances are excellent, the last half-hour is wonderfully bizarre and there's a surprising amount of humor in it, too. Not all of the humor is intentional, alas. But keep in mind Shyamalan ended his last film with a giant eagle flying in to save the day. Whatever you may think of him, you can't call him a chicken.