Gack is a cadet commando in Fighting Cats: an elite army unit of the Alai Duchy.
In the first chapter of the novel, Gack is mortally wounded in a dogfight with an attacking tank unit of the army of the Empire.
Even after Yashmaa proves to him that he is indeed on a different planet, Gack still thinks that he was sent to Earth with an unknown secret mission by the Alai military.
After a month since Gack's arrival on Earth, Yashmaa tells him that the war on Giganda was stopped by progressors and that the Alai Duchy as well as the Empire is no more.
In the last chapter, Gack is back on Giganda and helps local doctors cure a plague ravaging a nearby city.