The anime follows a group of friends Giulia, Maria, Enrico, Lucio and Angelo during the Seveso disaster as they team up with a Japanese journalist Shirou Andou, and begin their own investigation of what's occurring (during the week long period of exposure when the ICMESA refused to notify citizens of the poison). As many animals are dying and people are getting sick. The children and Shirou discover deadly dioxin was released and inform Enrico's father, the town mayor, who evacuates all the citizens. Shirou continues investigating more and learns of the negligence of La Roche, a company who controls ICMESA. La Roche knew they were in violating of existing safety laws/protocols and destroyed evidence of their crimes. The children attend a press conference to ruin La Roche's reputation as the destroyed proof might not be enough in a court of law to punish them.

Inochi no Chikyuu: Dioxin no Natsu was based on the Seveso disaster: a 1976 chemical accident that occurred near Milan, Italy.