Kosto's clear and systematic work is testament to his brilliance, not only as a historian, but also as a storyteller. The book itself is packed with wonderfully illuminating material on the medieval hostage, but also the analogous development of medieval power structures and society. The versatility of this book means that it would not only be of interest to a well-established historian (legal or otherwise), but also to a non-historian, or someone starting out in the field.