Sylvia, Felicia and Joan's new friend, has to drop out of school. Her dad, a trapper in the woods of northern Maine, has been accused of theft, and the evidence is stacking up against him. Felicia and Joan go home with Sylvia to keep her company for a few days, and while they are there, the three girls put on their skis and look for clues that would point to the real thief but find themselves looking at the wrong end of a rifle instead!