Florida skydiver Malcolm (Mac) Blackwell gets into trouble on his first solo jump due to twisted parachute lines and low altitude turbulence. He aims for a swamp for some chance at survival, but surprisingly passes through its bottom into an underground cavern, landing safely. Inhabitants of the cavern convince him to stay, at least for a while. How will Mac cope with this strange, unknown society? Many surprises lie in store for him that will change his future and the society into which he has fallen.