Michael Lewis investigates how high-frequency traders exploited technological advantages to extract billions from ordinary investors, and how a small group of Wall Street mavericks created a stock exchange designed to eliminate this advantage. The book follows Brad Katsuyama, a trader at the Royal Bank of Canada, who discovered that his large orders were being front-run: high-frequency traders detected his purchases milliseconds before they executed, bought the same stocks, and sold them back to him at higher prices. Lewis traces how this system developed, as exchanges sold co-location privileges that allowed trading firms to place servers closer to exchange computers, gaining microsecond advantages that translated into billions in essentially risk-free profits. Katsuyama assembled a team that mapped the complexity of market structure and eventually created IEX, an exchange with a 'speed bump' that neutralized high-frequency advantages. Lewis's narrative skill makes technical financial plumbing accessible, creating characters and conflicts that illuminate how modern markets actually function. The book sparked congressional hearings and regulatory scrutiny while also provoking criticism from defenders of high-frequency trading who argued Lewis oversimplified. Whether or not readers accept Lewis's framing, the book reveals a financial system more complex and less transparent than most investors imagine.