Ella Cockbain is a Research Fellow at UCL’s Department of Security and Crime Science. Her particular research interest is serious and complex crime - and its prevention. Her current research projects are focused on; human trafficking for labour exploitation; and sexual exploitation of boys. Her Ph.D. was among the first academic research into the internal (domestic) sex trafficking of British children. Ella collaborates widely with police and other practitioners and regularly delivers training and consultancy. Her publications include peer-reviewed journal articles and restricted reports for law-enforcement. This is her first book. Johannes Knutsson is Professor of Police Research at the Norwegian Police University College and has previously held positions at the Swedish National Police Academy and the Swedish National Police Board. He has conducted studies with and for the police for more than 30 years. Among other publications, he has co-edited several books on different aspects of policing: Putting Theory to Work. Implementing situational prevention and problem-oriented policing (with Ron Clarke); Evaluating Crime Prevention Initiatives (with Nick Tilley); Police Use of Force: A Global Perspective (with Joseph Kuhns); and Preventing Crowd Violence (with Tamara Madensen).