"The Big Short: Inside the Doomsday Machine" isn't so much "about" the financial crisis as it is about what caused the meltdown in the first place. Lewis tells his story through the actions of four separate investment groups: Scion Capital; managed by Dr. Michael Burry; FrontPoint Partners LLC, led by Steve Eisman; Cornwall Capital, co-managed by James Mai and Charlie Ledley; and Greg Lippmann, a bond trader with Deutsche Bank. These investors, each working independently from each other, correctly foresaw the collapse of the housing markets in the United States in 2007. Nobody else saw it – or wanted to, for that matter.

For years, many of the world's biggest investment and commercial banks had been investing heavily in high-risk subprime mortgages. This caused housing prices to rise, and a "housing bubble" to form. But soon, variable interest rates on these mortgages would begin to rise sharply, and massive numbers of people with little or no income would begin to default on mortgages they could no longer afford.