This introductory chapter sets out the key themes and arguments of the book and provides a road map for the remaining chapters. It outlines the book’s ambition to contribute to the sociological and criminological literature on technological infrastructures, borders and specific visions of Europe by portraying what we call the biobordering processes at work in the EU. Relying on what Misa and Schot, reflecting on technological infrastructures, have called the ‘hidden integration’ and ‘hidden fragmentation’ of Europe, the transnational exchange of forensic DNA data organized through the Prüm system serves as an exemplary case through which to explore the different logics of biobordering dynamics at work across the European Union. We complement an EU-level analysis with country case analysis of modes of biobordering that emphasize the legal, scientific, technical, political and ethical dimensions related to the governance and uses of biometric technologies both at a national level and in a transnational collaboration.