Beginning in the 1950s, alleged sightings of unidentified flying objects in Canadian skies bred tension between the state and its citizens. While the public demanded to know more about the phenomenon, government officials appeared unconcerned and unresponsive. Suspicion of government deepened among certain sectors of Canadian society in the decades that followed, leading to demands for greater public transparency and a new kind of citizen activism. In Search for the Unknown Matthew Hayes uncovers the history of the Canadian government’s investigations into reports of UFOs, revealing how these reports were handled, deflected, and defended from 1950 to the 1990s. During this period Canadians filed more than 5,000 reports of UFO sightings – many with striking descriptions and illustrations – with branches of government and law enforcement. Although the government conducted some exploratory studies, officials were unable to solve the mystery of UFOs or provide satisfactory answers about their alleged existence, and they soon declared the matter closed. Dissatisfied citizens responded by taking matters into their own hands, starting UFO clubs and civilian investigation groups, and accusing the government of a cover-up. A mutual mistrust developed between citizens who were suspicious of their government and officials who dismissed their fears and anxieties. This provided fertile ground for anti-authoritarian attitudes and the cultivation of conspiracy theories. In an era of political division, and amid heightened awareness of states’ responsibilities for their citizens, Search for the Unknown reveals the challenges that governments face in responding to public anxieties and preserving trust in public institutions.