Fishing guide John Kirby, a close friend of Macduff Brooks, takes a client up Cascade Canyon in Grand Teton National Park to fish for small brook trout. They find a body in Cascade Creek. He may have accidentally fallen in, or committed suicide, or been murdered. He was a Master Casting Instructor and around his neck on a string was a black fly. Fingers are pointed at Kirby and Brooks.


Further similar incidents occur on Mill Creek, a tributary of the Yellowstone River in Montana, and at a canal at Crystal River, Florida.


Brooks is accused of murder by the ambitious Attorney General of Wyoming, and by a prosecutor in Crystal River. Affecting the resolution of the deaths are problems with coroners and medical examiners, matching and phenotyping DNA, and the clash of politics, budgets, and justice.


Macduff and Lucinda are also drawn into dealing with Reginald Covington, the powerful Bahamian businessman who used his house to keep Lucinda for months of her subjection to Ellsworth-Kent's use of hypnosis.


Finally, Guatemalan President Juan Pablo Herzog learns something new about what happened to Professor Hunt.