Earthdivers (Earthdivers #8)

What started as a mission to find her missing twins in the Arizona desert in the year 2112 has landed Tawny in Ice Age Florida, separated from everything she knows and loves by thousands of years. But as the sole and unexpected protector of a new child in need, Tawny is more determined than ever to fight for survival in this chilling prehistoric world. And a surprising, devastating weapon she wields from the future may give a local tribe the upper hand in its battle against an invading Solutrean force.