It is the dawn of the 1960s. Stalin has been dead for eight years but his ghost casts a long shadow. In a place called Arzamas-16 - one of the most secret locations in the USSR, a place that doesn't appear on any map - a community of brilliant scientists, technicians and engineers have been tasked with creating the most powerful nuclear bomb the world has ever seen - a device three thousand times more powerful than Hiroshima. But one scientist has died an excruciating, grotesque death by ingesting a massive dose of irradiated Thalium. The Arzamas authorities believe it's suicide, want the body disposed of and the case closed, but someone in Moscow is concerned about what's going on in this strange, isolated and fiercely independent community.