What drives someone to commit the unthinkable?Austin 1966. Dunblane 1996. Port Arthur 1996. Utøya 2011. In this deeply insightful account, pre-eminent forensic psychiatrist Paul E. Mullen examines the complex psychology behind lone mass killers. With unflinching clarity, he burrows into the minds of these damaged individuals, drawing on his decades of forensic work assessing mass murderers first-hand. Mullen brings readers into a dark landscape populated with killers who have achieved the ugly fame they had sought - in the US, UK, Australia, Norway and beyond - as well as lesser-known, equally chilling cases. He illuminates troubling patterns that unite the perpetrators, such as obsessive rage, personal grievance, fascination with weapons and yearning for infamy, often culminating in suicide. He also considers the impact of media sensationalism on the killers' grandiose fantasies and proposes steps toward better threat assessment and identification of warning signs. Challenging myths around madness and violence, Mullen reveals the unsettling truth: these killers are not incomprehensible monsters, but profoundly disturbed people shaped by knowable forces that, when properly understood, can be countered effectively. Running Amok does not simply examine tragedy; it is a call to action, urging society to confront the shadows and prevent the next horror.