Money in politics is a little bit like an iceberg — there’s the stuff you can see, like lobbying firms, and then there’s all the stuff below the waterline. On this bonus episode from The World's partners at the Things That Go Boom podcast, host Laicie Heeley wades into the swamp. Heeley focuses on one of the loudest groups that weighed in on the Iran nuclear deal to get a better sense of how the system works. The story that emerges includes a Greek shipping magnate, a gold trader, an investigative reporter and the world’s largest collections of Rembrandts. The question at the center of it all: Is our foreign policy for sale?