In December 1998, San Antonio Express-News reporter Philip True vanished during a solo backcountry trek in western Mexico, home of the reclusive Huichol Indians and the Chapalagana, the Twisted Serpent Canyon, a 150-mile long gash that twists and plunges through the heart of the Sierra Madre. Five days later his editor, Robert Rivard, was part of a small search party that, nearly miraculously, tracked a trail of feathers that had leaked from...