The research project was only supposed to be for an "extended period." No one said anything about forever! So Riley's journey begins. Sent back 40,000 years to be the mate of a man she had never before met, Riley struggles to understand and adjust. Her journey will take her into a world fraught with dangers - a world made more treacherous by savage beasts, primitive Neanderthals, and the incursion of the aggressive Cro-Magnon man. Surviving alone for five years in this vast wilderness, Nathan, along with his enormous dog, Demon, carve out a life in the perilous environment. Though thrown together by forces beyond their control, love grows between Riley and Nathan - but will they survive?