Plant workers and firefighters try to control a catastrophic explosion at the Chernobyl nuclear power plant on April 26, 1986 in the USSR. 

With millions at risk after the explosion, Ulana Khomyuk tries to warn Legasov about a second threat. 

Lyudmilla ignores warnings about her firefighter husband's contamination. 

Legasov and Shcherbina consider using lunar rovers to remove radioactive debris. 

Legasov, Shcherbina and Khomyuk risk their lives and reputations to expose the truth about Chernobyl.