For decades, a complex network of bankers, brokers and investors managed to siphon billions from public funds without the intervention of politicians and the authorities. Those involved are said to have exploited a tax loophole in German law to secure multiple tax refunds for the same transactions; and these refunds amounted to sums well in excess of the amount of tax originally paid. By the time the relevant loophole was closed in 2012, the losses in tax revenue had already amounted to more than 30 billion euros. After years of painstaking investigations and numerous mishaps, a German court found in March 2020 that the cum-ex transactions were in fact a form of tax evasion. Investigations have since been launched into a growing number of those involved. This documentary looks back on the biggest tax evasion scam of all times: Who were the perpetrators, who unscrupulously abused the system? Why did the state stand by and watch? Did the protection of the banks ultimately take precedence over the interests of the taxpayer? And: What is still to come?