This first book on Kim Jong Un’s increasingly powerful sister, tapped to be his successor, offers jaw-dropping insights into the latest generation of North Korea’s secretive and murderous dynasty.

The first woman ever to issue the threat of a nuclear weapons strike is not even officially a head of state. Kim Yo Jong is the sister of North Korea’s Supreme Leader Kim Jong Un and, as their murderous regime’s chief propagandist, internal administrator, and foreign policymaker, she is the most powerful woman in North Korean history. Cruel but charming, she threatens and insults foreign leaders with sardonic wit, issuing proclamations and denunciations in her own name, a first for any woman in the Korean royal family. She memorably called the South Korean Defense Minister “a senseless and scum-like guy” before going on to promise South Korea “a miserable fate little short of total destruction and ruin”. A princess by birth with great expectations for her macabre kingdom, she was brought up to believe it is her mission to reunite North Korea with the South or die trying. She’s ruthless and incredibly dangerous.

The Sister, written by Sung-Yoon Lee, a scholar of Korean and East Asian studies and a specialist on North Korea, is a fascinating, authoritative account of the mysterious world of North Korea and its ruling dynasty—a family whose lust for power entails the brutal repression of civilians, a missile program that can reach the continental US, and the constant threat of global havoc.