FBI Agent Parr is going through a bad spell: his partner and best friend has just retired, and his wife has just left him. While investigating a robbery at a gun shop by a paramilitary gang, Parr and his new partner, Sinclaire, find clues to a plot to level the entire city of Chicago. Their main suspect is a recent Vietnamese immigrant with experience as a weapons researcher and a burning grudge against the U.S. Is he the man they're looking for? And if so, can they track him down before it's too late?