"In 1946, Günther Quandt—patriarch of Germany’s most iconic industrial empire, a dynasty that today controls BMW—was arrested for suspected Nazi collaboration. Quandt claimed that he had been forced to join the party by his archrival, propaganda minister Joseph Goebbels, and the courts acquitted him. But Quandt lied. And his heirs, and those of other Nazi billionaires, have only grown wealthier in the generations since, while their reckoning...