At its most basic, Andrzej Wajda's "Popiol i diament" (called "Ashes and Diamonds" in English) may seem to be a look at where Poland would be going after WWII ended. The plot involves young Maciek Chelmicki (Zbigniew Cybulski), who has helped expel the Nazis from Poland. With the Soviet Union now taking over the country, he is ordered to shift his allegiance to them. Through Maciek's acquaintances with communist leader Szczuka and barmaid Krzystyna (Ewa Krzyzewska), a potentially explosive situation arises.
If you know nothing about how the movie got made, this seems to be the whole purpose. But there are other points. In a mini-documentary about the movie, Andrzej Wajda and his collaborators explain how the novel on which the movie is based had Szczuka as the main character. Wajda not only moved the focus to Maciek - and gave him sort of a James Dean look - but also stressed the scene where Maciek talks with the man who fought in the Spanish Civil War. Apparently, fighting like the man did is a Polish tradition. Therefore, the film likely appeals to the Poles in almost every way; the perfect Polish movie, if you will.
Although I've never seen any of Andrzej Wajda's other movies - hell, I'd never heard of him until the Academy Awards gave him an honorary Oscar - I staunchly recommend this one. One can clearly see how he used the movie to subtly challenge the Soviet domination of his country (of course, they couldn't openly say anything against the USSR). Poland's pro-Soviet government had approved the movie, but didn't want to let it outside Poland. Wajda got some people to smuggle it out of the country, and it reached much of the world. Probably the most amazing scene is the end. I won't spoil the end, but I'll note that blood on a white sheet looks a bit like Poland's flag (a nationalistic statement).
All in all, a great movie. Andrzej Wajda has every reason to be proud of it.
