After a whirlwind cross-country move, Harriet and her donut-loving basset hound, Humphrey, have settled into a new life in Grass Valley, California. When Harriet learns that she's going to be a grandma for the first time and get a new suite with room for her salt-and-pepper shaker collection, she can't wait for her best friend, Martha, to come visit so she can share her good news.

But adventure is never far away when Harriet is around. After listening to the pleas of a desperate teen whose daddy needs money right away—and happens to have a gold mine to lease—Harriet falls hook, line, and sinker into the venture. Although she's nervous about her investment, Harriet chooses to keep it a secret from her son, Henry, and his wife. She can only imagine what she'll do if this turns out to be her ticket to a golden windfall.

When suspicions arise, though, it becomes clear that Harriet may never see an ounce of gold. But will she continue to trust and risk losing everything? The fate of the young teen and a family emergency show Harriet where her true treasure lies.