Last summer, 53-year-old Jeff Murphy was hiking in Yellowstone National Park when he disappeared. Park investigators found his body on June 9, where Murphy had fallen 500 feet from Turkey Pen Peak, after accidentally stepping into a chute. But he wasn't on just any hike. He was looking for a treasure box of gold and jewels worth up to $2 million, buried somewhere in the Rocky Mountains by an eccentric millionaire named Forrest Fenn. Fenn, an art dealer and millionaire in his 80s, lives in Santa Fe, N.M. In his self-published memoir, Fenn included a poem that supposedly leads to...