The film is based on real events. The series is set in the year of the well-known Chernobyl disaster. During the man-made accident, the nuclear reactor was completely destroyed. Tons of radioactive substances were released into the atmosphere. The Kremlin government is sending Soviet scientist Valery Legasov to the epicenter of events to gather important information, further investigate and eliminate the consequences of the tragedy. But during the investigation it turns out that the perpetrators of the largest man-made disaster are not going to be punished. Lies and falsification of facts reigns on every corner. Together with his partner, the hero tries to get to the truth.