On Aug. 20, 1910, the wind swept through the drought-stricken national forests of Washington, Idaho, and Montana, turning small blazes into roaring infernos that destroyed towns and timber in the blink of an eye. Forest rangers assembled nearly 10,000 men to battle the blazes, none of whom had ever seen such dramatic force before and knew nothing about how to subdue it. This is the story of the struggle between the overmatched rangers and of the tragedy that cemented Teddy Roosevelt’s legacy of conservation.