The Peril Finders - George Manville Fenn

In California settlers are trying to make a living working as fruit-growers. Problems with blights and insects mean that the crops are failing. A prospector arrives and tells stories of ancient cities where there is a lot of gold. He then dies. Some of the settlers decide to go and search for the gold. They have long distances to travel and meet many challenges along the way. They eventually reach one of these cities and find evidence that it has been abandoned by invaders hundreds or thousands of years ago. They then get attacked by Apaches but manage to beat them off and carry on. After spending several years travelling they decide to go back to California where they find that all the other settlers have left, but the fruit farms are blossoming. (Summary by Michele Eaton)