One in every five American adults is the customer of a family that you have never heard of. Their company generates more than $32 billion in annual revenue. And the $17 trillion in customer accounts and investment funds it manages exceeds the gross domestic products of Germany, Japan, and India combined. Yet despite Fidelity Investments’ enormous influence, relatively little has been known about the family behind the Boston-based multinational financial services giant.

In a new book, Justin Baer, deputy markets editor at The Wall Street Journal, reveals the dramatic three-generation saga of the fiercely private Johnson family and how they helped transform American investing.

This week, Baer shares the behind-the-scenes story of Fidelity’s success with roving reporter Rotbart, and the universal lessons Fidelity’s rise offers in leadership, marketing, innovation, and succession planning.