This is a fairy tale of true love turned tragic as Tsar Nicholas II, the handsome ruler of one-sixth of the earth, carries on the royal Russian tradition of marrying a German princess, Alexandra of Hesse. Their union produces four daughters and a hemophiliac son, the tsarevitch Alexis, whose disease only the evil monk Rasputin can treat. The stage is set for the downfall of the Romanov dynasty and imperial Russia and the coming of Communism. This entertaining and well-researched history traces the royal relationship and explores how a disease determined the destiny of rulers, the disintegration of the empire, and the course of Russian history.  (RUS69, $18.95)