It could be a turning point in the history of Iran. After years of sanctions - leading to cuts in oil exports - the Iranian currency, the rial, has suddenly halved in value leading to instant hardship and a strike by Tehran’s shopkeepers.
The Iranian government has arrested currency traders, blocked
foreign news channels and tried to suppress any information about the exchange rate.
Pooneh Ghoddoosi of the BBC Persian Service draws on the channel's remarkable cache of user-generated material to give a portrait of how the crisis has affected ordinary lives.
We hear the voices of ordinary Iranians who have called in to the BBC’s "Your Turn" programme - with their stories of life on the breadline.
Iranian students overseas - including in London - describe how they are suffering as their funding has dried up. We also talk to an Iranian banker, an industrialist and other analysts who will explain how the crisis has developed.
How much of it is down to sanctions and how much down the murky machinations of Iranian politics?
Pooneh also explores what the consequences could be, as the government faces its first popular protest for several years.
Can they pin the blame on the international community? Or will ordinary Iranians decide that enough is enough?