Nellie Burns and her faithful Labrador dog, Moonshine, leap into trouble-this time in Craters of the Moon in southwest Idaho.

Sheriff Asteguigoiri recruits Nellie Burns to accompany him to the lava fields as his official photographer. Three people have gone missing in the treacherous landscape, according to Tom, the mayor of a nearby town. Marked on maps for years as "unexplored" and "unknown," the miles of lava resist easy navigation as well as Nell's photographic efforts. Rosy Kipling-the one-eyed miner and Nell's friend-returns to Ketchum with his sons, and is enlisted along with Mayor Tom to assist in the search. In finding one of the missing persons, concerns arise about the questionable practices of a nearby religious group.

The efforts of Nell and the team yield unusual results-including large sums of money-while the Craters claim more victims in dark and mysterious caves, lava tubes, and spatter cones. Leather shields protect Moonshine's paws from a'a lava and abrasive cinders, but physical obstacles as well as secrets and lies, cult trappings, and consuming greed endanger the lives and limbs of all. Whether from accident or intentional injury, the members of the search party struggle to overcome the challenges of this remote and almost inaccessible natural phenomenon. And Nell faces the most serious attempt yet on her sanity and her life.