The Jewel in the Cave — John Moss

The discovery of awesome cave drawings by a disabled young anthropologist connects her to the precarious life of the girl who made them, fifty thousand years in the past. Angel Harris was born without the use of her legs. Her work is to explore caverns and tunnels others can't reach in the quest for fossilized human bones. Deep in the earth she encounters the primeval art of a young woman who calls herself MEme. Their two stories intersect. At fifteen, MEme emerged from her secret grotto to find her family had vanished. Horrified but undaunted, she sets off to rescue them from dreaded people we have come to know as Neanderthals. In the present, Angel is cast into subterranean darkness as she struggles to survive, only to realize that something in the world has gone terribly terribly wrong.