Hidden deep within central Soviet Russia is a place that doesn’t appear on any map: a city called Arzamas-16. Here dedicated scientists and technicians are building the most powerful nuclear device the world will ever see – three thousand times more powerful than Hiroshima. But days before the bomb is to be tested, a young physicist is found dead. His body contains enough radioactive poison to kill thousands. The authorities believe it is suicide – they want the corpse disposed of, the incident filed and forgotten.But Moscow is alarmed by what’s going on in this strange, isolated place. And so KGB major Alexander Vasin is sent to Arzamas to investigate. What he finds there is unlike anything he’s experienced before.