"Chernobyl" dramatizes the story of the April 1986 nuclear plant disaster which occurred in the Ukrainian Soviet Socialist Republic, Soviet Union, telling the stories of the people who were involved in the disaster and those who responded to it. The series depicts some of the lesser-known stories of the disaster, including the efforts of the firefighters who were the first responders on the scene, volunteers, and teams of miners who dug a critical tunnel under Reactor 4.