“Some secrets protect imperial power, some secrets protect the people oppressed under said power.” Beginning with the Byzantine scholar Procopius’s The Secret History, an early-medieval text that promised to reveal the sordid secrets of the Byzantine emperor Justinian and his wife Theodora, Betancourt ponders the role of secrecy in past eras and its continuing appeal in the present. He explores the Mandylion, a textile concealed within a reliquary box, on which the face of Christ was allegedly imprinted; the Limburg Staurotheke, an elaborate box containing fragments of the True Cross and intended to be used on the field of battle; the marvelous automatons housed in the Great Palace of Constantine VII Porphyrogennetos; and the “illustrious secret weapon” known as Greek fire, which the Byzantines deployed against enemy ships in war and that made them masters of the sea. The uses of these mysterious objects and the secrecy that surrounded them reveal a great deal about stratagems of imperial power: Greek fire, for example, was “transmitted and preserved through closely knit networks of secrecy,” allowing the empire to retain a monopoly on its use for centuries. Betancourt, a self-described “queer scholar of color,” beautifully captures the exotic allure of Byzantium and the knowingly deployed mechanisms that make the medieval empire a continuing source of fascination, while also drawing apt analogies for more recent events such as the war in Ukraine. He shares stories of monks born as women who might today be identified as transgender, writing movingly of their acceptance by their communities and demonstrating that trans people have not always been maligned, even in an era now often perceived as regressive. Conspiracy theories like QAnon, he writes, are “exercises in how a populace imagines the secret things of imperial power,” presenting their adherents with a “radical” sense of “future possibility.”