The fortress city of Dirraxis has long been drifting in the sky at Permissible Heights. Within the powerful Sound Barrier, people managed to relax and establish a normal and completely safe life. They did not remember about death hidden in the thickness of the clouds. The pilots forgot the feeling of fear in front of the face of the bloodthirsty Sounders. Only those who flew beyond the barrier knew how short life was. Few wanted to join them, and few were ready to hear the frightening howl of the city siren again. Few were ready to remember what the war of survival meant. One day the first layer of the barrier was destroyed, one day hundreds of thousands of people died, and one day the fate of an ordinary city boy changed. He, obsessed with the desire for revenge, obsessed with the thirst to feel the power of a strike combat aircraft under him, took the path of a military pilot. The road ahead of him was not easy.