TRIAL BY FIRE: A Woman Correspondent's Journey to the Frontline By Kathleen Barnes (Thunder's Mouth Press: $19.95; 256 pp.) . Kathleen Barnes chases stories written in blood. Covering that kind of carnage, from Northern Ireland to the Philippines, should be a young person's job, but Barnes came to it in her mid-30s, fleeing a pleasant life as a reporter on a small-town daily in Upstate New York, the wife of another reporter perfectly content to cover a place she found stultifying. Her book is an absorbing memoir of her six years in the midst of the depravity born of intractable religious and political differences. If it does not cross the line to art--if she fails to step back and describe events with the perspective available to someone not meeting daily deadlines--it is still a valuable reminder of the outrages people (too much like us) commit in the name of God and state.