In 1991, a former U.S. naval intelligence worker, Milton William Cooper, published Behold the Pale Horse, an extremist manifesto that purported outlandish conspiracist claims, from the Illuminati, to JFK, to predictions of extraterrestrial invasions, perpetuating a cult of conspiracy and mistrust that persists to this day. In the Pale Horse Rider, journalist Mark Jacobson not only tells the story of Cooper's fascinating life, that ended in a fatal...