A diversion dam―about six feet high and several yards across―is alongside Mill Creek in Paradise Valley, Montana. The owner of the dam annually opens the dam to allow water to his farm in late summer and early fall. All of the water is diverted causing the creek to become waterless and all the fish to perish.
The farmer, Oscar Macpherson, refuses to allow even a small amount of water to remain in the normal course and allow the fish to survive. One morning his body is found at the bottom of the now closed dam. He may have fallen, or he may have been struck from behind. A coil of yellow line was found on his body.
Macduff and Lucinda are concerned because it happened within a mile of their log cabin, and they have both been outspokenly opposed to Macpherson's use of the diversion dam.
Dan Wilson in D.C. asks Macduff and Lucinda to go to Guatemala and help Luisa Solares, Herzog's niece, escape his grasp. Nancy Jones, now married to Herzog, has become his First Lady by marriage, and Vice President by election. He is jealous of her.
Lucinda would like to have Dan approve her killing Herzog to protect Macduff. They go to Guatemala, but things go wrong when Herzog shows up at the U.S. Embassy while Luisa is being helped leave the country.
Two new persons, wealthy twin brothers Bob and Dave True, move to Paradise Valley and want to rid the valley of miners, diversion dams, depletion of well water by agriculture, and ripraps along the Yellowstone River. How they will change matters becomes a problem, by legal means of buying land, or murdering those who abuse the land.
