1:23:45

Lore & Background

The story opens in 1988 with Legasov recording tapes about the accident, hiding them, and then taking his own life. It then moves back two years to the night of the explosion.

In the control room, deputy chief engineer Anatoly Dyatlov, played by Paul Ritter, refuses to accept that the core has exploded, even as workers report what they have seen. Operators are sent to open water valves by hand and receive lethal doses. Firefighter Vasily Ignatenko is called out to the fire while his wife watches from their apartment.

Plant managers and the local committee decide the damage is under control, refuse an evacuation and cut communication with the outside world. An engineer who reports the exposed core is sent to the roof to look again and receives a fatal dose. By morning Legasov has been told to advise the government committee, and smoke from the reactor is drifting towards the town.

Filming began in April 2018 in Lithuania. A residential district of Vilnius stood in for Pripyat, and the plant scenes were shot at the Ignalina Nuclear Power Plant, which has been closed since 2009.

Reader's Guide

Critics received the premiere with widespread acclaim, praising its atmosphere, its cinematography, the realism of its depiction of the disaster and the performance of Ritter. Several reviewers gave it five stars. A review in The Guardian was cooler, awarding three stars and finding that the episode left viewers with unanswered questions while still praising the acting.

The title is the time on the clock when the reactor exploded, at 1:23:45 AM on April 26, 1986. The episode also uses that time for the death of Legasov. That choice was made for dramatic purposes; in reality he died a day later.

Mazin began researching the project in 2014, reading books and government reports and interviewing nuclear scientists and former Soviet citizens. He said he wanted to avoid adding to the problem of falsehood by over-dramatizing the story. A companion podcast was released alongside each episode, beginning with this one. The episode won three Primetime Creative Arts Emmy Awards.

Did You Know?

• The producers first intended the lead role for Daniel Day-Lewis, who retired from acting shortly before the series was announced.