Beginning with a hundred-mile hike to reach Hawks Rest, Ferguson recounts his adventures observing grizzly bears, tracking wolf packs, and encountering other wildlife in what is now the largest intact ecosystem in the temperate world. Along the way he meets an intriguing array of backcountry hikers, park rangers, elk hunters, outfitters, and wildlife biologists all grappling with the challenges of preserving this magnificent slice of wilderness.

Cahill stumbles from glacier to geyser, encounters wildlife (some of it, like bisons, weighing in the neighborhood of a ton), muses on the microbiology of thermal pools, gets spooked in the mysterious Hoodoos, sees moonbows arcing across waterfalls at midnight, and generally has a fine old time walking several hundred miles while contemplating the concept and value of wilderness. Mostly, Cahill says, "I have resisted the urge to commit philosophy....