Satania
"Charlotte - aka Charlie - a pretty redhead, sets up an expedition to find her brother. The young scientist, who disappeared underground several months ago, claimed - to everyone's astonishment - to be able to prove the existence of Hell by using Darwin's theory of evolution! The little group, led by Charlie, plunge underground in his pursuit. The deeper they progress into the entrails of our planet, the more they enter another world that hides other forms of life heretofore never experienced. The discovery changes them gradually in a way they cannot perceive" -- provided by publisher.