The film opens in New York. People start to get confused in Central Park, repeating their words, standing still and sometimes walking backwards. We hear a few screams. A woman reading on a bench takes her silver chopstick-style hair pin out of her hair and stabs herself in the neck with it.
In the next shot, we see a science teacher named Elliot Moore (Mark Wahlberg), talking about the event science can not explain about thousands of disappearing bees, no bodies left, no trace. A student offers the opinion that this is a natural event that we will never fully understand. While speculating on the phenomenon that is the disappearing bees, Elliot is suddenly called out of class to a staff meeting warning about an apparent “terrorist attack” in New York in which terrorists have apparently released some kind of gas in Central Park, and advising that school is cancelled. As they leave, Elliot confesses to his friend Julian (John Leguizamo), a math teacher, that he and his wife are having some problems.