The Stasi were among the most successful security and intelligence services in the Cold War. Behind the Berlin Wall, colleagues, friends, husbands and wives, informed on each other. Stasi chief, General Mielke, prided himself on this situation. Under Marcus Wolf, Stasi agents were spectacularly successful in gaining entry into the West German Establishment and NATO. Some remain undiscovered. Now, for the first time in English, two British experts...