A perfect storm of torrential downpours, gas well fracking and earthquakes created a massive sinkhole swallowing up two twelve-year-old boys who were searching for dinosaur fossils. They find themselves deep in the earth's underworld embarking on an unbelievable journey through a labyrinth of tunnels deep in the hollow of the earth. There, they discover a civilization that evolution forgot, which assists J.P. and Caleb through numerous life threatening encounters, guiding the boys to the surface.