Meet Grandfather, an ex-military hero, and his two curious grandchildren with their pet dog Muffin. Grandfather is in for a surprise when he finds the children and Muffin have stowed away inside his military plane. The family finds themselves captive in a strange inner world after their plane flies into a large dark hole in the Antarctic. Little do they know that they will be in the grips of the evil ones. In their adventure below the Earth's crust, they are rescued by a gentle Lady and her king through supernatural means. The family is sent back to the surface to help save all of humanity from being enslaved by a hidden evil that lurks in the depths of our own planet Earth!