Bestselling true-crime author Christopher Berry-Dee’s latest book tackles the heavy crime of people who randomly kill large numbers of others (spree killers) and those who set out to do so in specific places or situations (mass killers).

As such killings become more frequent, the ready availability and ease of obtaining firearms and weak backgrounds checks in the United States inevitably lends to many of these cases, but there have been other recent examples in the United Kingdom, New Zealand, and Norway, where extremely robust firearms legislation could not stop these horrific crimes. What is more difficult to establish is the motivation behind such killings. Some are occasioned by grievance, real or imagined, while others have their origins in a sense of failure or feelings of inadequacy, yet others seem to be driven by a desire for power over their fellow humans, often coupled with an overriding contempt for the lives of others. In a search for answers, Christopher Berry-Dee offers case studies in some of the most infamous mass killings of the past fifty years, from school massacres to workplace killings, hate crimes to familicides. But is the awful truth that such murderers are almost impossible to predict and therefore almost impossible to prevent? Dig in and find out.