Two weeks ago a huge underwater volcanic eruption ripped open the seabed in the North Atlantic. Since then, several ships and three Royal Navy submarines have disappeared in that area without a trace!

You play the part of Captain Henson, pilot and designer of the deep salvage rescue sub 'Anttilis', which has been slightly redesigned and re-equipped for this mission...
You have been asked by the Government to make a one manned deep probe expedition of the fissure and find out what is going on down there...