THE ASSASSIN. 3 stars. Set in the waning days of the Tang Dynasty, Hou Hsiao-Hsien's film is full of stillness, the carefully observed, as it follows a serene and hard-to-read woman trained in the martial arts on an assignment she is reluctant to fulfill. Not "Crouching Tiger, Hidden Dragon," and certainly not "Kill Bill," but a film that evokes the spirit of the genre at the same time that it transcends it.