Violet finally learns the name of the strange music she's been hearing in the woods, “Abime des oiseaux…” She visits Ms. Twombley at the Question Mark Public Library, looking for answers. Ms. Twombley remembers that there is a book that mentions a British soldier also hearing music in the woods.

While searching for the source of the music, Violet and Nanako find teeth that seem to belong to several pets in the woods. Where will this strange clue lead her? And what, or who, will disappear next?