Black Sun Descending — Stephen Legault

Silas Pearson is plagued by nightmares. In them, his wife, Penelope, who has now been missing for four years, shows him where murder victims are buried across the Colorado Plateau. One such dream leads him to the Atlas Mill tailings site, outside Moab, Utah. There, Silas discovers the corpse of anti-uranium-mining activist Jane Vaughn, who went missing from Flagstaff, Arizona, buried in radioactive waste. Trying to connect the murder with the disappearance of his wife, who was friends with Vaughn, Silas travels across the Southwest to the North Rim of the Grand Canyon. He confronts a host of suspects who wanted Jane Vaughn dead and who believed Penelope, too, was interfering with progress on the plateau. All the while, Silas's nightmares, threaded with snatches of prose from the writings of Edward Abbey, seem to be leading him to some final confrontation -- but with what?

This is the second book in the Red Rock Canyon Mysteries, all of which are set in the American Southwest -- around Arches, Canyonlands, and Grand Canyon National Parks, and the Grand Staircase-Escalante National Monument.