Planet Sansion does not rotate around an axis. On one side there is eternal darkness, on the other - blinding day. And between them there is an insurmountable barrier - the distortion of light and space - Granmir. Ships are fighting in the skies, and even higher soars an impartial judge - Klavier - a society in whose hands is the most valuable resource on the planet, the source of all energy - the wind. In the midst of a battle between two states, the pilot of a courier ship, Olya Valentinova, receives the task of delivering a “package” to its destination. This cargo turned out to be a girl, and the place where she should be taken was a ship, the captain of which was the most wanted criminal. The girl has a twin sister. And together they are the mysterious “key to the wind”, which is capable of changing the planet and making it the way the ancestors who once flew from Earth intended. But Klavier is not ready to part with what he considers his own. In the end, such despotic rule turned the rest of the world against him.