When he was just twenty-two years old, Charles Darwin joined the crew of the H.M.S. Beagle as naturalist and traveling companion to Captain Robert FitzRoy. During the subsequent journey—in which FitzRoy conducted a hydrographic survey of the coastline of South America—Darwin amassed a wealth of scientific evidence that shaped his understanding of the natural record and, ultimately, led to his development of the Theory of Evolution. Origin tells the story of this historic voyage and the relationship that developed between Darwin and Fitzroy—a relationship that drew Darwin deeper into science and pushed Fitzroy deeper into religion.