Tradition has 18 weapons in the Chinese martial arts.
A nationalistic clan tries to use their kung fu to block bullets, but it has proven to fail. An expert in the clan disbands the part under his control, and now the rest of the clan is after him. This expert is skilled in all 18 legendary weapons of China, so the order is to kill anyone who is associated with the 18 weapons. But how can they find the real expert, who has now escaped to Canton, when there are millions there?