This is a review and a summary of some of the key arguments presented by Mian and Sufi in their recent book “House of Debt.” It highlights the contribution of Mian and Sufi by showing how they have solved the mystery of why there was a huge drop in aggregate demand during the Great Depression of 1929 and also following the recent Global Financial Crisis of 2007-08. The article shows how major economists like Keynes, Friedman, Lucas and others tried and failed to provide an adequate explanation of this mystery. The key to the mystery is the huge amount of levered debt present during both of these economic crises. The solution suggested by Mian and Sufi is to replace interest based debt by equity based contracts in financial markets. This solution resonates strongly with Islamic teachings on finance. These links are also highlighted in this article.