This chapter sets the thematic and methodological foundations of this book. It introduces Lake Urmia’s transformation from a once thriving ecological and cultural landmark to a degraded hypersaline environment—a shift framed as a ‘mutation’. The chapter outlines the relevance of this framing to question the human–nature divide and for situating the crisis within hydro-social and Latourian perspectives. Based on this premise, the chapter formulates the central research questions: what drives hydro-social dynamics at Lake Urmia, which actors are held accountable in the socio-scientific discourse, and what controversies reveal deeper conceptual conflicts about the crisis. The chapter explains the scope of the inquiry, emphasising the scientific discourse while incorporating supplementary perspectives from other stakeholders. Finally, the structure of the thesis is presented, detailing how subsequent chapters address theoretical background, historical water governance in Iran, the scientific landscape of Lake Urmia, and the main controversies under study. By the end of this chapter, the reader has a clear understanding of the research aims, conceptual framework and roadmap guiding the investigation.