My husband was the first one at our house to notice that something had gone terribly wrong in an Arizona wildfire on June 30, 2013. It was Sunday, early evening, and we were home having pizza and wine with our neighbors. My husband brought some dirty dishes to the kitchen, and stopped to scroll through Twitter. He saw that nineteen firefighters had gone missing and were presumed dead in a fire that was burning along the western edge of an out-of-the-way town called Yarnell. I grabbed some clothes, my laptop, my cell phone and portable charger. I apologized to the neighbors, said goodbye to my husband, told our daughter, "Mommy will be back soon," and started driving.

That night, and for eight days after that, I anchored the New York Times' coverage of the fire. I found out that the nineteen firefighters had died at the bottom of a canyon, and that the canyon had been covered in thick, parched brush when they entered it. I knew these firemen all belonged to the same crew, the Granite Mountain Hotshots, and I quickly learned three things about them: They were well-respected as a crew that got the job done, and done well; they were young, healthy, ambitious and incredibly fit; and they knew fire.

They were five hundred yards from a ranch when they came face to face with a wall of flames forty, fifty feet high. Still, none of them broke rank. None of them ran.

Why?