The introduction takes the reader into the history of oil in the Ecuadorean Amazon in the twentieth century. Zooming out from the testimony of a former oil worker, a historical overview sheds light on the dynamics of oil extraction in the region by national and international companies. This history is analyzed from the interdisciplinary perspective of the Environmental Humanities, combining archival and oral sources, sociological and anthropological concepts, and a mixed-methods approach. From this vantage point, the changes in the rainforest brought by the oil industry can be narrated as a fundamental metamorphosis of the landscape, its ecology, and its inhabitants. Drawing from Amazonian and European notions of metamorphosis, four dimensions of this process are particularly relevant for the historical analysis: conceptual, material, toxic, and social. The metamorphosis as metaphor offers a perspective on historical change in the Amazon as a process driven by the conflictive interaction between the rainforest ecosystem and the narrative and material manifestations of the oil industry.