IN 1902, WILLIAM HORNADAY handed a map to the famous paleontologist Barnum Brown. It was Hornaday’s hand-drawn directions to a remote area of the Montana Badlands, where he believed amazing dinosaur fossils lay buried. Following the map, Brown dug up a jawbone edged with six-inch long teeth, the remains of a monstrous creature no one had ever seen before. But one bone wasn’t enough, and Brown soon found himself in a desperate race to discover the skeleton of the mystery carnivore!