In alternate chapters, Colt moves from a quest to understand how his own brothers shaped his life to an examination of the complex relationships between iconic brothers in history. The author believes that he would be an entirely different man had he not grown up in a family of four brothers. In this book, he movingly recounts the adoration, envy, rivalry, affection, anger, and compassion in their shifting relationships from childhood through middle age. He discusses how Edwin Booth grew up to become the greatest actor on the nineteenth-century American stage while his younger brother John grew up to assassinate a president. He shows how Will Kellogg worked for his older brother John Harvey as a subservient yes-man for two decades until he finally broke free and launched the cereal empire that outlasted all his brother's enterprises. The author also relates how Vincent van Gogh would never have survived without the support of his younger brother, Theo; how Henry David Thoreau's life was shadowed by the early death of his older brother, John; and how the Marx brothers collaborated on the screen but competed offstage for women, money, and fame.