Venezuela's Angel Falls has ceased to exist. Atop Auyán tepui, one of Venezuela's remote table mountains, an offshore earthquake causes the opening of a deep, narrow canyon that swallows up Angel Fall's Churún River which then flows into a large cave. At the rear of the cave, the river disappears into an abyss that is speculated to be over twenty-five hundred feet deep. The existence of this abyss is brought to the attention of group of extreme cave explorers. Exploring deep difficult caves is what these people do; it is what they live for. The group organizes an expedition to explore the cave, and their primary mission is to be the first to rappel into this monster underground pit. Accomplishing this would be a monumental caving first, and they are extremely excited about the prospect. Early on, they notice that the cave walls are extremely smooth and unusual, and they suspect that something unnatural was behind the formation of the cave. Their encounter with a competing Russian expedition confirms this suspicion. As they overcome massive difficulties,interference by the Russians, and near success, they make a discovery that they could never have expected. This discovery changes the direction of their expedition, imperils their lives, and sends them scurrying on an extended trek that takes them from Venezuela to one of the most remote islands in the arctic north in quest of an artifact that may save their lives.