An informative examination of cryptocurrency, focused on criminals using it for nefarious purposes (drug deals, theft, child abuse) and the agents, researchers, and corporations that have helped track them down. Greenberg offers a balanced view  that also speaks to the aspirational benefits of an unregulated, theoretically private money market, but ultimately the heros here are the dogged civil servants. While he did his best to explain in layman's terms, I still struggled at times to understand the analysis techniques, and the story could be repetitive and dry as it covered case after case. Yet it's useful reading to understand a transformative industry and also how bad actors could be anyone hiding in plain sight.