A herd of wild mustangs stopped in the middle of the desert when they spotted a female park ranger hanging off a cliff — thirty seconds later, what they did left the entire rescue team speechless. Across southern Arizona, a two-lane ribbon of asphalt runs past weathered fence posts and a sunburned water tower, then gives itself to canyon light. At the outpost, floodlights hum. Radios murmur. Heat lifts from the rock like a living thing. Far from the road’s last mile marker, a cliff face opens it