The narrative follows a group of frontier boys who travel into the Canadian Rockies and face a succession of rugged adventures: raging torrents, treed by a lynx, mountain-lion and grizzly encounters, vanished ponies, mysterious caverns and volcanic terrain, and brushes with outlaws and Indian bands. Episodes alternate high action with demonstrations of practical courage and quick thinking, including rescuing a ragged runaway youth whose origins and family connection are gradually uncovered. Lawmen and a mounted trooper contribute key revelations that bring a criminal plot to light and resolve the central mystery.