1976, Northern Italy. In July 10, an incident in the "ICMESA" implant provokes a chemical fallout over the town of Seveso, not far from Milan. A massive cloud of dioxin comes out from a damaged reactor, falling down on the earth and causing one of the most terrible ecological disasters in history. For days, the "La Roche" corporation which owns the factory tries to minimize the incident, so that Seveso's inhabitants persist to stay in their houses, exposed to the dioxin's deadly effects.