In 1949, Kazimierz Moczarski, a leading member of the Polish resistance, was in his fourth year of incarceration when he was moved into a cell with two Nazis at Warsaw’s Mokotów prison. One of them was Jürgen Stroop – a war criminal and SS general who had led the infamous destruction of the Warsaw ghetto and was responsible for the murder or capture of more than 56,000 Jews. They shared the same four walls for 255 consecutive days.A celebrated figure in modern-day Poland, Moczarski was regarded as a threat to the power of the postwar communist regime in the country....