At the heart of cybersecurity is a paradox: Cooperation enables conflict. In Age of Deception, Jon R. Lindsay shows how widespread trust in cyberspace enables espionage and subversion. The dark arts have long been part of global politics, but digital systems expand their scope and scale. Yet success in secret statecraft depends on political context, not just sophisticated technology. Lindsay provides a general theory of intelligence performance--the analogue to military performance in battle--to explain why spies and hackers alike depend on clandestine organizations and vulnerable institutions. Through cases spanning codebreaking at Bletchley Park during WWII to the weaponization of pagers by Israel in 2024, Lindsay reveals continuity and change in secret statecraft. Along the way he explains why popular assumptions about cyber warfare are profoundly misleading. Offense does not simply dominate defense, for example, because the same digital complexity that expands opportunities for deception also creates potential for self-deception and counter-deception. Provocative and persuasive, Age of Deception offers crucial insights into the future of secret statecraft in cyberspace and beyond.