When several people in Philadelphia fall victim to a what seems to be a nerve-agent, Hood, Rachel and Felix get called in. Using maps and recreating the victim's morning commute, Hood determines all the victims intersected in a corner of subway station and that they crossed paths with a man who had something in his backpack spray them. The find the man with the backpack, dead in the corner and realize that he was traveling to a theater to meet others: their intention to use all the children at the afternoon performance as hostages (threatening to use their nerve-agent on all of them) in order to get the G8 meeting in nearby Washington to release political prisoners.
