(SPOILER ALERT: There's a lot of plot details for season 4 ahead.)  "The Iron Bank will have its due," is not as widely recognized a phrase as the Stark family motto "Winter is Coming," but it may end up being almost as important to the outcome of the series.  "Whether history or fantasy, the game of thrones prevents the spread of sound economic ideas, and precludes good economic policies," Matt McCaffrey, a post-doctoral academic in Liberal and Integrative Studies at the University of Illinois who has written previously about the economics of "Game of Thrones," told CNBC via email.  These countries are winning the 'Game of Thrones'  The Seven Kingdoms of Westeros is pretty much a basic feudal economy, generating very little income of its own. Instead, it has turned to the nearby Free Cities—each of which has a bank and a thriving trade in spices, cloths or slaves—for loans to fund its campaigns.  The Iron Bank, located in city state Braavos, seems to be the most powerful. The Bank appears to be an example of a "too big to fail" lender—so if one king or another doesn't start paying its debts, there could be trouble ahead. This is a real case of example of "sovereign debt."  Tycho Nestoris, the most prominent envoy of the Bank, is being introduced to the TV show this season—earlier than in the books. He is played by well-known British actor Mark Gatiss. HBO confirmed "this part of the story is quite integral" to season 4, which begins Sunday.  Game of Thrones and Walking Dead face-off  It can be said that Cersei Lannister's hold on the throne starts to weaken not when rumors start about who is the real father of her children, but when she stops paying the Iron Bank. Unfortunately for her, the throne is distinctly sub-prime at this point, and the Iron Bank quickly transfers allegiance to her enemy Stannis Baratheon.  So is the Iron Bank a little like the International Monetary Fund or World Bank in backing particular horses in one country? Well, for example, there were rapid changes of governments in the euro zone's stricken countries as they struggled to impose austerity measures imposed by international lenders like the International Monetary Fund during the region's debt crises.
In the world of the HBO series “Game of Thrones,” it’s not just the fire-breathing dragons which drive the plot, but gold dragon coins.