First, an accident occurred that resulted in the death of a person. Then came suicide. Then — murder. All this would look scary anywhere. And on board the international space station, these incidents look simply terrifying. Which of the station's nine inhabitants is the killer? Everyone is a suspect. Meanwhile, the mysterious killer puts forward his demands to the presidents of Russia and America, promising to kill the inhabitants of the station one by one if they are not fulfilled. And he immediately proves that his threats are not a joke...