The first chapter introduces the book’s guiding question: What is the role of affect and emotion in international criminal law and transitional justice? Instead of accepting at face value the commonly held assumption that the law systematically neutralizes affective dynamics, I argue that the law purposefully creates, mobilizes, shapes, and transforms affective dynamics by curating atmospheres and producing sentiments. This chapter introduces the analytical and conceptual framework, defines the main terms ‒ affect, emotion, atmosphere, and sentiment ‒ and opens up the ethnographic focus on the case The Prosecutor v. Dominic Ongwen before the International Criminal Court.