April 30, 1986. After bribing her way into Hospital Number 6 in Moscow, Lyudmilla flouts a nurse's warnings about limiting her contact with Vasily. With the reactor fire finally contained, Legasov warns Shcherbina that a plant meltdown could contaminate drinking water for 50 million people. Determined to uncover the cause of the explosion, Khomyuk goes to the hospital to interview the men who were on the scene, drawing unwanted attention from the KGB. As miners dig a tunnel under the reactor to stave off a meltdown, Legasov lays out a decontamination plan for surrounding areas that will require drafting hundreds of thousands of men.