You may not be entirely prepared for “The Notebook,” which is neither a Southern romance with Rachel McAdams and Ryan Gosling nor a typical treatment of Holocaust themes with kids at its center. Two Hungarian boys are left in the care of the grandmother during the Nazi occupation of Hungary in 1944, and they vow to toughen themselves up to brace for whatever their uncertain future holds. World War II was about as brutal as modern human existence gets, particularly across a Europe ravaged not just by bombs and battlefields but starvation, disease, and various high corruptions. “The Notebook” definitely captures that last bit, but doesn’t allow us an awful lot of sunlight, even where the newly hardened boys are concerned. Perhaps a more accurate look at the civilian damage of the war than we’re used to seeing, “The Notebook” is nevertheless awfully grave viewing.