The book is narrated by Beverley, who together with his brother Felix, has come to live with his Aunt Janet and Uncle Alec King on their farm while their father travels for business. They spend their leisure time with their cousins Dan, Felicity and Cecily King, hired boy Peter Craig, neighbor Sara Ray and another cousin, Sara Stanley. The latter is the Story Girl of the title, and she entertains the group with fascinating tales including various events in the King family history. The book is actually two stories; those of Beverley King and his friends, and the tales told by the Story Girl.