Explores the history and principles of camouflage, revealing how deception and disguise have shaped espionage from World War I to modern times. Published to accompany the Spy Museum's new exhibition, this illustrated book presents four key principles of camouflage, and shows how deception and illusion underpin espionage. Before its military adoption, naturalists and artists studied how animals and birds vanish into their surroundings. As technology transformed warfare in the early 20th century, these insights were applied on the battlefield and labeled camouflage during World War I. Beyond blending in, disruptive patterns- dazzle -were used on ships to distort perspective and hinder submarine attacks. The threat of long-range aerial bombing in World War II led to disruptive coloration and concealment being used on airfields, essential factories. The long ties between theater, Hollywood, stage magic, and clandestine services produced notable masters of disguise in World War II, using their skills to hide and conjure up entire armies. Stories of humans in disguise have been seen throughout human history and culture, and disguise sits at the core of deception. Changing identity can determine success or failure in espionage. Mimicry is as essential for undercover assets as for animals: agents must be able to not only look the part, but inhabit new identities, maintain double lives, and deceive everyone they meet. Beyond charting camouflage's history and impact on covert operations, the book also considers the implications of modern detection technologies on camouflage-and spies-in the future.