Stellan Skarsgard and Emily Watson have signed on to star in “Chernobyl,” the HBO and Sky nuclear disaster miniseries. The five-parter will dramatize the tragedy that took place at the titular nuclear plant in 1986 and the subsequent investigation.

Skarsgard (“Mamma Mia”) will play Boris Shcherbina, head of the Bureau for Fuel and Energy of the Soviet Union and leader of a government commission investigating the disaster. Watson will star as Ulana Khomyuk, a Soviet nuclear physicist committed to solving the scientific mystery of what led to the accident.

The project reunites the pair after they worked together on 1996 movie “Breaking the Waves.” Jared Harris (“The Crown”) has already been confirmed to play Valery Legasov, the Soviet scientist chosen by the Kremlin to investigate the accident.

Skarsgard said: “Nobody would see it as a privilege to spend five months in a dilapidated nuclear plant, unless it was to play in a script like this by Craig Mazin, work with a director like Johan Renck, collaborate with a producer like Jane Featherstone, jam with an actor like Jared Harris and finally be at the feet of Emily Watson whom I have been missing for some 20 years.”

“This is a significant piece of work and I’m honored to be part of it,” added Watson. “I can’t wait to get started with this amazing group of people, and am especially excited to be working with Stellan again.”

The series, produced by Sister Pictures and The Mighty Mint, is the first Sky-HBO project to be greenlit under a $250 million co-production deal. Shooting starts this spring, in Lithuania.