A woman park ranger has an accident during a survey of New Mexico's Carlsbad Caverns, a 300-mile labyrinth of caves and tunnels 800 feet underground. Fellow park ranger Anna Pigeon braves her claustrophobia to mount a rescue and discovers it was no accident

For six exciting years Doug Thompson worked as a park ranger at Carlsbad Caverns National Park. Here, he passes along the essence of what he learned on this unusual job and in his related adventures exploring the surrounding Chihuahuan Desert. He overcame his fear of tight spaces and heights, learned to climb rope, and went on to explore many of the deep vertical caves in the Guadalupe Mountains of western Texas and southeastern New Mexico - including...