In 1950s and early 1960s Hong Kong, radio permeated in everyday life as a major source of entertainment and information. It subsequently gave rise to a peculiar genre in Cantonese cinema, film adaptations of “airwave novels” (tiankong xiaoshuo dianying 天空小說電影), which flourished in Hong Kong and Southeast Asia. According to the records of the Hong Kong Film Archive, from 1949 to 1968 there were ninety-three film adaptations of radio novels and dramas. Besides drawing the historical contours of the radio-film network in the postwar colonial city, this article studies two exemplary radio stories-turned-films, Niehai chihun 孽海痴魂 (A Devoted Soul; 1949) and Cimu lei 慈母淚 (A Mother's Tears; 1953), and scrutinizes their transmedial/transnational adaptation trajectories to shed light on intermedia aesthetic criticisms. This article describes how film technology reconstituted the oral and spoken in audiovisual space, in particular the embodiment and representation of the radio acoustic. The voice-over, indicative of the radio unconscious in the film, registers the existence of a consciousness already programmed by radio sounds that reconfigures the economy of filmic diegesis. This article further investigates how such medium self-reflexivity in the form of voice-overs destabilized the Manichean structure of melodrama as an established genre in Cantonese cinema, thus making space for forms of female agency amidst contending ideologies in early Cold War.