The first atomic explosion in history not only transformed global politics - it also left traces in photographic materials. Eva Castringius explores how radiation from the 1945 Trinity test became inscribed in photosensitive materials, producing images that register the event beyond what could be seen. Bringing together photographic theory, media history, and new materialist philosophy, she shows how nuclear processes interacted with photographic materials and how historical events persist in material traces. Her photographic series Within Active Territory, created on the grounds of the Trinity test site, opens the book and connects the historical event to the site's present physical condition.