During a scientific expedition in Iceland, visionary scientist Trevor, his nephew Sean, and their beautiful local guide Hannah are unexpectedly trapped in a cave. Their only escape is to go deeper into the depths of the Earth. Traveling through never-before-seen worlds, the trio comes face-to-face with surreal unimaginable, and terrifying creatures. The explorers soon realize that as volcanic activity increases around them, they must find a way back to the earth's surface before it is too late.