An adventure film of a different sort--the fascinating record of the exploration of Castleguard Cave under the Columbia Icefield in Banff National Park, an exhausting but irresistible crawl through more than 5 km of dark tunnel, the longest known in Canada. What beckons the members of the expedition, what they find, how they support the physical stress, the nagging doubts, and what their reward is--these are all questions they answer in this film.