THE BORDER-LINE MYSTERY, #1 in series.
Edition: Early printing.
New York & Cleveland: World Syndicate (c 1930). Hardcover - The first book in the Airplane Boys series, featuring Jim Austin and Bob Caldwell and their plane, originally published as Airplane Boys on the Borderline, and previously published as Sky Buddies Series #1, "The Air Mystery of Isle La Motte.. 246 pp.
Condition: Very good in red cloth with pasted on illustration on front cover.