When a run-in with the local bully means the boys risk losing their beloved dog, Cody, they hatch a plan to keep him safe. They'll take him to live with their grandmother in the Sierra Nevada mountains. He'll be safe there, and Grandma--who lives off the grid--will benefit from the companionship. But first they've got to figure out exactly where in the mountains she is.

Following clues left in postcards and pictures and using their keen senses of deduction and survival, they finally find her tract of land. But when they get there, they discover that a group of ill-intentioned developers is trying to bully her off her property. Do the boys have what it takes to outsmart the developers and save their grandmother's beloved home?