Planet Money reporter Chana Joffe-Walt asks a simple question: Who was the federal regulator who was supposed to be regulating AIG? The answer turns out to be far from simple.

Alex Blumberg and NPR correspondent (and "Planet Money" reporter) Dave Kestenbaum examine what went wrong with the credit ratings agencies. When all these financial instruments that brought down our economy—the mortgage backed securities, the derivatives—were originally issued, the rating agencies (Standard and Poors, Moody's and Fitch) gave many of these things their top rating of triple-A.

Ira goes to Chicago's Rogers Park neighborhood to talk to some condo owners who are in a precarious situation—since the housing market crash, the developer who renovated and sold them their units—Haso Meseljevic—has all but disappeared. He's in foreclosure on half of their building's units.

NPR reporter and Planet Money contributor Chana Jaffe-Walt reports this story of what it really looks like when a bank fails and is taken over by the FDIC. She talks to the former employees and a handful of FDIC staff about the Friday night when the Bank of Clark County was interrupted and closed by 80 FDIC employees, who had every step of their secret operation down to a science.

Alex Blumberg and Adam Davidson tackle a very tough subject: Trying to explain exactly what a bank is and does. They talk to a number of experts about what has gone wrong in banking, but not before bringing us all up to speed on some banking basics, like understanding a bank balance sheet, and a bank's assets and liabilities, and the squishy business of what banks say about their balance sheets compared to what they are.Alex and Adam walk us step by step through the complications of the US government buying up bad assets from banks, and explain why, when it comes to footing the bill, the government might just prefer to not be in charge of the very banks it is having taxpayers bailout.

Not everyone hates the idea of "toxic assets." Reporter Lisa Chow goes to New Jersey to follow two guys on their quest to clean up some of America's bad mortgages—by buying them, and going straight to the homes themselves to have a look at how dire the situation really is.

To deal with the financial crisis, our own government has also had to reinvent itself, with questionable consequences. This American Life producer Alex Blumberg and NPR's financial reporter Adam Davidson talk to Brad Setser, an economist at the Council on Foreign Relations who used to work at the U.S. Treasury.

Alex Blumberg and Adam Davidson recount the 36-hour period, two weeks ago, when the credit markets froze. Plus, what it's like now for businesses to get short-term loans, and how the hardship is spreading to every sector of the economy.

One more confusing financial product that's bringing down the global economy. And one of way to think about this product is this: If bad mortgages got the financial system sick, this next thing you're about to hear about, helped spread the sickness into an epidemic.

Ira talks with Michael Greenberger, a former commodities regulator, who tells the story of when it was decided not to regulate credit default swaps. And how that decision was emblematic of the way we didn't regulate a lot of the toxic financial products we're hearing about now.

This American Life producer Alex Blumberg teams up with NPR's Adam Davidson for the entire hour to tell the story—the surprisingly entertaining story—of how the U.S. got itself into a housing crisis. They talk to people who were actually working in the housing, banking, finance and mortgage industries, about what they thought during the boom times, and why the bust happened.

Alex and Adam's story continues.