The Motor Boys over The Rockies
, the 10th volume in the series, starts with the boys trying to decide where to go on summer vacation. But they soon discover—the Comet, their dirigible/airplane has been stolen! Yoicks! What a dastardly deed! Have no fear; our heroes find their air craft and along with Professor Snodgrass, who joins them as the Comet is leaving the ground—literally—westard they go! Hearing of a group of men being held captive in a remote canyon in the Rockies, the boys decide to do the only thing they can—rescue them! Easier said than done, they soon learn.