In The Camp Fire Girls Solve a Mystery; Or The Christmas Adventure at Carver House Katherine Adams arrives in Oakwood expecting to be met by her friend Nyoda but finds herself alone and confused. After a series of misadventures she stumbles upon an empty house where she hears a mysterious voice singing. Inside she meets Sylvia Deane a spirited young girl who pretends to be a princess to cope with her difficult circumstances. Sylvia's aunt who cares for her has been injured in an accident leaving Sylvia alone and without food. Katherine moved by Sylvia's plight decides to take her to Nyoda's home Carver House where she is warmly welcomed by Nyoda and her friends the Winnebagos. As the group settles in for the Christmas holiday they become intrigued by the history and secrets of Carver House. Sahwah one of the Winnebagos is particularly curious about a locked room in the house which turns out to be the study of Nyoda's late uncle Jasper. Inside they discover a beautiful stained glass window hidden behind an iron shutter. The group is puzzled by the shutter's presence as it seems to mar the beauty of the window and the mahogany casement. Nyoda recalls that her uncle was a reclusive and eccentric man but she is unable to explain the shutter's purpose. The group enlists the help of Hercules an old servant who worked for Uncle Jasper hoping he can shed light on the mystery. However Hercules is evasive and claims his memory is failing. Despite Nyoda's attempts to coax the truth from him Hercules remains tight-lipped leaving the mystery of the shuttered window unsolved. The story weaves together themes of friendship curiosity and the allure of uncovering hidden secrets set against the backdrop of a cozy Christmas gathering.