Dr. James "Mac" McKenzie, a recently-retired Central Oregon veterinarian, has just lost his wife to breast cancer and starts out alone -- with only their family dogs -- on a cross-country RV road trip to thank people who made a difference in their lives. His experiences as a United States Army Special Forces veterinarian in Thailand during the Vietnam Conflict quickly surface as bio-terrorists adopt techniques he worked on during his tour of duty. Government agencies -- some whose loyalty he questions -- need his help in locating the terrorists, a search that involves old friends, his...