The book discusses how China is working to make its currency, the RMB, more important globally. It explains why China wants this, how Hong Kong is involved, and why it's hard for the US dollar to stay on top forever. The book uses simple economic ideas to show that for the RMB to succeed, China needs to make its financial system better and more open. It also says that the RMB will likely become a major payment currency, behind the USD and euro, but ahead of the Japanese yen.