New York: A. L. Burt, (1932) dj. Hardcover first edition - While vacationing in Green Falls, Michigan with her aunt Emily and the usual crowd, Linda and her friend, Dot Crowley, take a pleasure jaunt in Linda's autogiro over Lake Michigan to Wisconsin. During the trip, the girls witness a hit and run accident, in which a girl is struck by a car and thrown into a ditch, unconscious. The girls land and take her to a hospital, but when it turns out that she has amnesia, they take her back to Green Falls. Part of what makes this series unusual is the aircraft which Linda files - an autogiro, a precursor to the helicopter. Jennifer White notes "The final two volumes are truly rare,. . They are just about impossible to find and seldom come up for sale. Many years can pass with neither volume 4 nor 5 surfacing" and even more rare are copies in dust jacket. Green and white illustrated endpapers. Original receipt from a dry goods store in Rochester, NY laid in, showing a 25c price. 247 pp plus 8 pp publisher's ads.