Set in the middle of the fifteenth century tensions are high between the Kingdom of Korea and the more powerful Chinese Empire with the latter trying to dominate the former. The Koreans have secretly developed a new weapon but Chinese agents have found out and stolen the calculations required to develop the weapons. The Inventor is killed but his daughter escapes and helps continue the work on the weapons. There are many difficulties in the development; they must get the ingredients to make the gun powder and they still need the calculations. Inevitably the two sides will eventually meet in battle and the new weapons will finally be tested