The Outdoor Girls in the Air; or, Saving the Stolen Invention

4.5 stars
Not of high literary value, but a fun, clean story of girls solving a mystery. Stella's flight instructor has invented a new mechanism, but his “sponsor” tells him it is worthless. When the young pilot is found drugged, Stella and the girls are certain that something is up. It doesn't help that the young man suffered shell-shock in the Great War and has forgotten his own identity. Perhaps the invention isn't so useless, after all...