In ancient China, it was a long established tradition for the Emperor to be protected by a special squad of undercover guardsmen. Guardsmen Gong, Xi and Cai excel in the skill of martial arts, while Fa is untrained in martial art, working as a gynaecologist as his cover. The other guardsmen and the Emperor look down on him. China's neighbouring country, Jin, had always wanted to invade China. By propagandising the dissection of an extraterrestrial being, its King plans to attract all medical doctors to Jin and have them killed. Then China's soldiers would be left with no doctors to care for the wounded, and they would be no match for Jin's invading army. However…