Candice Millard is the author of three books, including this one. The other two are The River of Doubt: Theodore Roosevelt's Darkest Journey and Hero of the Empire: The Boer War, a Daring Escape and the Making of Winston Churchill. Her work has also appeared in the New York Times Book Review, Washington Post Book World, the Guardian, National Geographic and Time magazine.

James Garfield is at the center of the book, which is about his presidency, assassination, and medical care. Born in 1831, in Mentor, Ohio, he was raised in poverty after his father died when he was two. However, he managed to go to Western Reserve Eclectic Institute, a preparatory school, where he excelled in his studies. After graduating from Williams College in Massachusetts, he returned to the institute to teach, later becoming its president when he was only 26 years old.

He married his wife, Lucretia, in 1858, and entered politics, first as a state senator, and then as a US Congressman, elected in 1862. When the Civil War broke out in 1861, however, Garfield had joined the army, so his early years as a lawmaker were spent on the battlefield. He worked his way up to brigadier general before President Lincoln urged him to take his seat in Congress, where he served for seventeen years.