When I began work on my first book, 'The River of Doubt,' which tells the story of Theodore Roosevelt's 1914 descent of an unmapped river in the Amazon rainforest, I thought of it as a tale of adventure, exploration and extraordinary courage.

When I began work on my first book, 'The River of Doubt,' which tells the story of Theodore Roosevelt's 1914 descent of an unmapped river in the Amazon rainforest, I thought of it as a tale of adventure, exploration and extraordinary courage.