Benedict Cumberbatch has been cast as KGB Agent Alexander Litvinenko in HBO’s upcoming limited series, Londongrad. The Oscar-nominated actor and his company, Sunnymarch, are also executive producing the drama, which is currently in development, Variety is reporting.

The show is based on Alan Cowell’s 2008 book, The Terminal Spy, which recounts Litvinenko’s life story. He was famously poisoned with the radioactive isotope polonium-2010 while he was in England in 2006 after he defected from Russia.

Twenty-two days after his hospitalization, Litvinenko died in the hospital.

Much like the book, Londongrad will depict the agent’s life story as well as the investigation into how his assassination was even pulled off. Before his death, he gave media interviews and making statements from his deathbed. Litvinenko claimed the poisoning was ordered by Russian President Vladimir Putin, as similar assassinations and attempted assassinations had also been linked to Putin critics.

The project is being written by Academy Award winner, David Scarpa, who’s also serving as an executive producer, alongside Cumberbatch.

Bryan Fogel, who won an Oscar for his documentary, Icarus, in 2018, is set to direct, as well as serve as an executive producer on, the series. The actor’s colleagues at Sunnymarch, Adam Ackland and Claire Marshall, will also executive produce the series with Fogel, Scarpa and Len Amato. HBO has not yet announced when it will air Londongrad.

Cumberbatch, who’s known in part for playing legendary detective Sherlock Holmes on the BBC series, Sherlock, isn’t the only actor who’s preparing to portray Litvinenko on screen. The annoucement of the Golden Globe-nominated actor’s casting in Londongrad comes after Doctor Who star, David Tennant signed on to portray the title role in the ITV drama, Litvinenko, last month.