Some secrets remain buried forever . . . When holocaust survivor, Jossi Goldberg, is found dead near his house in Frankfurt, a five-digit number is discovered scrawled in blood at the scene of his murder. The autopsy shows the victim has an old tattoo on his arm which connects him to Hitler's SS, making detectives Pia Kirchhoff and Oliver Bodenstein question Goldberg's true identity. Two more deaths reveal a link between the victims, but what is the secret they shared that the killer seems desperate should go no further? What else happened in the aftermath of the Second World War in Europe yet to be uncovered? Pia and Oliver follow a trail which leads them back to those dark days of wartime in the hope that they can find an eyewitness who may be able to come forward with the truth.