Introduction -- Borders: thick and thin ; Part I: The Perimeter. The Wall and its shadow: security in the borderlands -- One border, two sovereigns? -- Co-bordering, cosmopolitanism and the specter of empire ; Part II: The Ports of Entry. The tiniest constable: big data, security and the Politics of Identification -- Sovereignty, security and the Politics of Trust -- Into the digital dark: data, the global firewall and the future of security