Egan documents, in The Big Burn, the forest fire of 1910 that burned three million acres in Washington, Idaho and Montana, and brought Theodore Roosevelt's vision of conservation to the forefront of the national consciousness.

Why did you decide to write about this fire?

I was looking for a really good core story, a dramatic clash with nature built around a larger story of individuals who were trying to do something for society. This amazing wildfire that killed nearly 100 people and burned an area the size of Connecticut in less than 36 hours has deep, lasting impact 100 years later.

You shift between minute-to-minute accounts of the fire fighting and the national stage, where Teddy Roosevelt and Gifford Pinchot, chief of the Forest Service, share a mystical vision about the future of America.

History usually gets told from the point of view of the great man. I tried to tell a parallel story about the people who don't normally make it into books, the heroic people who are just asterisks to history against the larger tableau of the Roosevelts and Pinchots.

Pinchot is a strange sort of hero: people don't like him very much; he's mentally unstable; and he has this puppylike devotion to Roosevelt. What drew you to his story?

He fascinates me. You have this guy from an incredibly wealthy family who is considered the founder of American forestry—out of guilt, because his grandfather was a clear-cutter—devoting himself to this progressive cause of letting the average guy have a piece of something, which is what public land is all about. And imagine if President Obama and his top aides went skinny dipping in the Potomac or stripped to their shorts and boxed at night? That's the kind of relationship Pinchot and Roosevelt had.

Roosevelt is a larger-than-life character; how do you contain him within a story that really isn't about him?

I wanted to portray Teddy Roosevelt the outdoorsman, the person who gave us our public land philosophy. The more you read about Roosevelt, the more you're struck by his energy and his ability to multitask. He wrote more books before his 40th birthday than most great authors write in a lifetime. He climbed the Matterhorn and rafted down the River of Doubt, an uncharted river in South America. He had so many different lives. And through it all, he changed American society through his progressive ideals. The fact that we have labeling on our food is largely a result of Roosevelt's ideas about meat inspection. The fact that we have public land is largely his. The fact that we have national parks? His. He's this amazing individual with all these facets, and the changes he brought to society are still with us.