Olivia Langdon was born into what became the richest family in Elmira, New York, in 1845, and was one of the first females in the country to attend a college. But her life became extraordinary when she married Mark Twain in 1870. As the wife of the man who was destined to become the best known, and perhaps best loved, American in the world, she would befriend the literary elite of America and Europe, travel around the globe, and dine with royalty.

But her life was filled with tragedy. Her son was born prematurely, was never healthy, and died when he was a year and a half old. Her...