Lewis begins with the story of Sergey Aleynikov, a computer programmer for the major investment bank Goldman Sachs. The FBI arrested Aleynikov in 2009 for stealing his employer’s computer code. He was described as a “high frequency trading programmer” during the proceedings but no one could explain what that meant (2), or what exactly his crime was. Lewis explains that financial markets’ participants often court disaster without quite understanding what they are doing or the consequences of their actions for the sake of making a hypothetical profit. The stock market is even riskier now than it was when Lewis began his investigations in the 1980s. The popular image of people yelling on a trading floor is no longer relevant; stock trading is now the domain of computers whose operations are far too fast or complex for any person to understand, even those that designed the algorithms. These markets are hopelessly opaque to the average investor and the broader public. Lewis explains these changes through the anecdotes of people like Aleynikov at the center of high frequency trading.