In Northern Ireland, it takes an assassin to catch one, in this thriller by "the John D. MacDonald of espionage fiction" (Larry McMurtry, The New York Times).   As the Troubles rage in Northern Ireland, a mysterious killer has been putting bullets in victims' heads one by one--with no apparent pattern or logic. Now Joe Gall has been tasked with quietly looking into the matter by a high-ranking American cabinet official who fears his son may be involved. Gall sets out to find the boy and bring him home alive--if possible. But the story behind the murders may be more complicated than it seems . . .   "I admire Philip Atlee's writing tremendously." --Raymond Chandler