In Frankfurt, tax lawyer Dr. Bernd Hausner and the young Sven Lebert set up a fund based on the double refund of capital gains tax: so-called Cum-Ex transactions.

Hausner and Lebert realize that their business partner, Fred Allen, has been cheating on them for years; they can't report him. For the first time, Lebert considers a future without his mentor.

Young tax official Anna Nowak refuses to reimburse Hausner and Lebert's funds worth millions. She informs public prosecutor Lena Birkwald, who takes over the case.

Public Prosecutor Birkwald and her team are slowly becoming aware of the extent of the cum-ex transactions. She is pursuing a plan to conduct simultaneous searches in 16 countries.

Lena Birkwald succeeds in making the extent of tax fraud clear to the Finance Minister of North Rhine-Westphalia. But Birkwald also wants to get to grips with the institutions themselves: the banks.