At 3 p.m. on August 17, 2013, a hunter’s illegal campfire crept out of control near Yosemite National Park. The fire spread through dry underbrush along Jawbone Ridge, licking up the trunks of ponderosa pines, searing and scorching until entire treetops burst into flames, flinging sparks and glowing needles skyward. On August 21 the fire, now known as Rim, went on a rampage, exploding over rocks and leaping the Tuolumne River, torching stands of centuries-old pines and plantations of young trees in a red-hot rage that blackened more than 125 square miles in just two days. By the time it was finally extinguished on October 25, the Rim fire had consumed 402 square miles of forest, an area 11 times the size of Manhattan. Eight months later Ryan Burnett surveyed the scene from a crest overlooking the Tuolumne watershed. Ridgetop after ridgetop was covered with dead trees, some with needles scorched rust from the heat, others singed bare. Not a single green tree stood in the vast and...