When two passenger airplanes collide over the Grand Canyon in the 1950s killing all aboard, John Clarke's body is lost, as is the briefcase of diamonds he had locked to his wrist. Scorning Mr. Clarke's pregnant fiancée, the Clarke family disclaims the out-of-wedlock daughter, Joanna Craig. When Clarke's father dies without heir shortly after the crash, the family fortune is entrusted to the estate's attorney, Dan Plymale, to create a charitable foundation. Mr. Plymale then proceeds to live well as executor ofthe foundation's funds, while Joanna Craig and her mother make their own way.
Decades later, Billy Tuve, a Hopi, is arrested on suspicion of burglary and murder based on his presenting a rare diamond for pawn. Tuve's cousin, Cowboy Dashee solicits help from his friend Navajo Tribal Police Sergeant Jim Chee to clear Tuve's name. Retired Lieutenant Joe Leaphorn recalls that his old acquaintance Shorty McGinnis acquired a similar diamond many years ago from a man whose story matches Tuve's story. Then Louisa Bourebonette relates the stories she has heard from older Havasupais about the man with the diamonds living at the bottom of the Grand Canyon, and the flyers from a woman seeking her father's remains from that plane crash, which Leaphorn shares with Chee. Joanna Craig pays the bail for Billy Tuve, asking him to lead her to the place where he received the diamond. Though it will aid his case, Billy is reluctant because the place, the Salt Shrine, is sacred to his religion. Before Joanna can pick Billy up at his own home, Fred Sherman takes Billy away. Joanna trails them, and in a quick maneuver, takes Sherman's gun from him and shoots him in the chest. She and Billy proceed to the trail head on the south rim of the Grand Canyon. Billy takes her part way down, then disappears. Bradford Chandler, hired by Dan Plymale, learns Sherman will not meet him when a police officer answers Sherman's cell phone. Chandler goes on alone, arriving near the sacred spot. Chee, Dashee, and Bernadette Manuelito arrived earlier, looking both for the absent Billy and the man who long ago traded with Billy, a religious hermit wanting people to believe more in Massau’u, to resolve their feelings after the plane crash, with bodies raining down on them. Manuelito stays behind while Chee and Dashee each go a different way along the canyon bottom. She does not stay in one place, but walks and finds the slot (a cave but with an opening to sunlight way above) along the canyon wall where the man had lived, and his body, long dead of natural causes. She sees a human arm bone, and his array of the 70 remaining diamonds. She finds what Chee and Dashee sought.
Chandler, with his loaded pistol, meets Joanna in the canyon bottom. An uneasy pair, they follow Manuelito's tracks into the slot, where she is ready for the murderous Chandler. Chandler stores the seventy odd diamonds in his hiking socks. A "male" storm, one of high intensity rains, rises. Manuelito and Joanna Craig take shelter on a ledge, while Chandler leaves with his diamonds and is then carried out by the force of the instant river made by the rain. Chee finds the slot in time to see the corpse carried out by the torrent of water, followed by Chandler. He tries to save Chandler, but Chandler will not let go of the socks full of diamonds. The storm passes, and Chee runs to Manuelito. The three meet Dashee, whose ankle is injured, and return in the rescue helicopter. Joanna Craig has what she needed most, the remains of her father's arm, once chained to the container of diamonds. New DNA analysis methods show positively that he was her father, and she claims her true name of Clarke. She now has the basis to sue Plymale for her inheritance. Sherman was found in time by the local police, and survives. He will not admit that petite Joanna Craig shot him; instead he tells police he did it himself by accident. The two corpses were found, but not the diamonds, save for the one taken by Bernadette as evidence in favor of Billy Tuve. Billy Tuve is proved innocent of theft and murder.