In the ancient heroic epics, the romantic feelings of the brave warrior disappeared in the sound of mechanical shooting. For a hundred years, the pursuit of efficiency has been the pursuit of killing. Firearms are the highly crystallization of human wisdom, and also an amazing engineering miracle. The documentary "Gun" draws on the concept of similar foreign documentaries, takes the army firearms as the main introduction object, takes the legendary stories of old guns and new guns in China and around the world as the entry point, focuses on the reasons for the improvement and upgrading of world famous weapons, analyzes the advantages and disadvantages of weapons and their impact on specific campaigns, and reveals the relationship between war, weapons and technology.