In this intelligent, wide-ranging memoir, Ash Carter, President Obama’s final secretary of defense, outlines the challenges and intricacies of working in the Pentagon and shares his organizational philosophy. Carter’s experience with the Pentagon started during the Carter administration, when he advised on potential storage options for ballistic missiles. Though he served the Reagan, Bush, and Clinton presidencies, his main focus here is on his years leading the Department of Defense in the Obama administration. Carter lays out his approach to working with the president (for example, “pitching in during meetings rather than holding back,” a practice Obama appreciated), the department (as secretary of defense he opened all positions to women and removed the ban on transgender soldiers), Congress, and the public as the secretary of defense, before outlining needed actions for foreign policy (“updating our war plans, improving our acquisition performance both in peacetime and in wartime, building bridges to the high-tech community, and modernizing our talent management systems”), and exploring the international threats he labels CRIKT (China, Russia, Iran, North Korea, and terrorism). Carter writes clearly and accessibly about the complexities of the Department of Defense, employing a level of detail that might be more appreciated by historians than the average reader, but the pacing is brisk and the insights into the work of the Department of Defense are informative.