"Shadow Dancer," about an IRA partisan recruited as an informant by MI5, creates a powerful mood of unease and sustains it for an hour and forty minutes. There are scattered moments of intense beauty throughout, thanks to Rob Hardy's widescreen photography, which tends to view people from either very far away or very close up, making you think about them as individuals and then as specks in a social panorama. And yet for all its beauty and intelligence, the movie is unsatisfying. Why? The story of, essentially a civil "Cold War" between Irish and British forces is so innately powerful that we should feel for the characters a great deal more than we do.