From Here To Atlantis

If a second journey were being made delving into the earth after an earthquake opened a passageway -- one that will take you to ancient ruins of a subterranean village that may have been originally part of Atlantis, would you go? And what if on a high ledge above that village you find a remnant of a time capsule from space that existed before the time of Atlantis, one that could take you back to that lost civilization, would you make the ultimate time journey?
Sloan Abbott, a bookish academic with the learned ability to successfully remote view, is added to the crew chosen to make the second journey inside a new fissure in the earth to locate a missing British explorer. He is chosen by Lesley Hayden, world-traveled archaeologist. Both are interested in the legend of the lost civilization of Atlantis, Sloan having seen it from the air in a remote viewing session. Lesley also believes that it actually existed. Ex-military leader of the expedition, Alan Rhinehart, clearly believes that Sloan's being a scholar does not qualify him for a possibly dangerous mission. Marvin Chou is the timid electronics expert who comes to believe that Sloan does not like Asians because of a bad experience with an Asian girl friend.
After their decent beneath the earth in a vehicle called the Mole-Car, they discover an abandoned ancient village enclosed in a pocket of barely breathable air and faintly glowing cavern walls. Gradually accumulated evidence leads them to believe that this is a remnant of the lost civilization, pushed inside the earth by an extraterrestrial projectile that struck and destroyed the civilization. At one point, Alan abandons the crew by stealing the Mole-Car but returns with a new crew whom he recruited for suspicious purposes. Sloan and Lesley climb inside the cavern walls and ascend to one of the high ledges which supports a temple. Marvin remains in the city and is joined by Alan's crew of freebooters.
Inside the temple, Sloan and Lesley discover a piece of the projectile that originally struck Atlantis, only to realize that it is machine sent through space to gather information along a timeline. Both of them have visions of Atlantis. Lesley disappears and Sloan is eventually swept up into a vortex -- a time tunnel which deposits him with a tribe of woman who are enemies of Atlantis. He gets involved in a battle and is taken prisoner, only to meet Sir Percy, the British explorer who had been party of the first party to explore inside the earth.
When he eventually ends up in the center of Atlantis, he meets Lesley in the guise of a beautiful lady of royalty -- her own distant ancestor. Sloan develops a relationship of sorts with the now-captive leader of the tribe of agricultural women, but she is threatened when she and the other women prisoners are put into an arena to die at the hands of Atlantean gladiators. Sloan, Percy, and Lesley must also decide which of them is to return to deal with Alan and the others back in the subterranean village in our own time. The other two want to remain in Atlantis and take their chances with the fleeing survivors. Some choice!