A man walks into a trendy Los Angeles restaurant—a disgruntled ex-employee with an automatic weapon—and seconds later, thirteen people are dead and thirty-two more have been wounded. It is a heinous act of mass slaughter that haunts Homicide Detective Peter Decker.

Though eyewitnesses saw only the lone gunman—who apparently took his own life after his bloody work was done—evidence suggests more than one weapon was fired. It is a disturbing inconsistency that sends Decker racing headlong into a sordid, labyrinthine world of Southern California money and power, on an investigation that threatens to destroy his reputation and his career.