In this, the second book of the Ruth Fielding series, Ruth goes to boarding school with her best friend Helen. When they get there, Ruth starts her own sorority called the SweetBriars for the new girls. Her sweet group of girls conflicts with the two other sororities the Upedes and the Fussy Curls. In the midst of settling in to the new place, there is a campus rumor about a legend of the marble harp playing ominously at night. But when the French teacher is in a fright, will Ruth be able to solve this mystery?

The Ruth Fielding series has influenced several other major series that came later, including Nancy Drew, the Dana Girls, and Beverly Gray.

Brave, adventurous and loyal, recently-orphaned Ruth Fielding is sent to live with her estranged Uncle Jabez at the Red Mill in Cheslow, New York. A new town means making new friends, and the teenage Ruth quickly befriends the children of a wealthy merchant. But as the relationship between her and her uncle becomes strained and she attempts to become friends with a very disagreeable girl, will Ruth's cheery disposition be enough to get her through?

This is the first of the Ruth Fielding series, with follows Ruth and her friends from adolescence into early adulthood.