1929. From the 26 volume Mystery and Adventure Series for Boys. The Flight of the Mystic Owls begins: In the wide expanse of the river valley there was only one moving figure, that of a strong Indian pony carrying its erect rider. They were headed toward the more narrow canyon which opened from the apparently impassable mountains ahead. The road wound in and out, to right and left, as the natural barriers suggested. At the right lay a waving stretch of long grass swept now and then by a breath of wind; and beyond, where the line of willows and alders indicated the presence of a stream, the narrow, dashing river made its way. At this elevation there were no farmhouses or cultivated fields to be seen.