During the 1950s and early 1960s, the American film industry produced a distinct cycle of films situated on the boundary between horror and science fiction. Using the familiar imagery of science fiction, the vast majority of these films subscribed to the effects and aesthetics of horror film, anticipating the dystopian turn of many science fiction films to come. These films often evinced paranoia, unease, fear, shock, and disgust. Not only did these movies address technophobia and its psychological, social, and cultural corollaries, they also returned persistently to the military as a source of character, setting, and conflict. Commensurate with a state of perpetual mobilization, the US military comes across as an inescapable presence in American life. Regardless of their genre, this book argues that these films have long been understood as allegories of the Cold War. They register anxieties about two major issues of the time: atomic technologies, especially the testing and use of nuclear weapons, as well as communist aggression and/or subversion. Setting out to question, expand, and correct this critical argument, the book follows shifts and adjustments prompted by recent scholarly work into the technological, political, and social history of America in the 1950s. Based on this revised historical understanding, science fiction films appear in a new light as they reflect on the troubled memories of World War II, the emergence of the military-industrial complex, the postwar rewriting of the American landscape, and the relative insignificance of catastrophic nuclear war compared to America's involvement in postcolonial conflicts around the globe.