In the third and final film, the Robinsons celebrate the arrival of spring after surviving a fierce winter. Soon their happiness is quickly dashed, as a Forest Service ranger informs them they must prove their mountain home is located on a legitimate mining claim which is on government land or they must move out. Also, Pat finds out that her mother is ill and decides to go back to Los Angeles. Will the Robinsons lose their mountain home? Will Pat come back from the city?