This clever and gripping book, written in the manner of the 9/11 Commission’s report, takes as its starting point the United States’ failure to get North Korea to give up its nuclear arsenal. It then imagines that the North’s air defenses shoot down a South Korean civilian airliner, sparking a crisis that escalates rapidly to nuclear war. Although the book is a work of fiction, each step in the plot is backed up by research into past incidents and current capabilities. The war snowballs thanks to a risky retaliation by South Korean President Moon Jae-in, undertaken without consulting the United States (the part of the book that is the least convincing). The crisis is worsened by the dys-function of the Trump administration—including, inevitably, a tweet from U.S. President Donald Trump that convinces North Korean leader Kim Jong Un that the South’s attack is part of a coordinated effort to topple his regime. Although the plot is not entirely persuasive, one does not have to accept every aspect to appreciate Lewis’ warnings about the dangers of poor communication within governments and between states and how exaggerated claims by leaders, for example, about the effectiveness of their missile defense systems, create risks.