A time between Ice Ages.
Golau, a Cro-Magnon hunter gatherer, is pulled from a freezing lake and nursed back to health by a group of wandering Neanderthal. Miles away, his clan's peaceful existence is torn apart by an attack from an unknown predatory species and many are taken beyond the ice wall as prey.
Golau and some of the remaining men set out in pursuit and are joined by a pod of Neanderthal, seeking answers of their own.
During the quest, the two species are forced to forget their differences and work together despite some uncomfortable truths being revealed.
Back in the Clan, those left behind are forced to change their ways very quickly if they are going to survive the oncoming winter and a young feisty girl with strange ideas leads them down a path completely alien to what they have always done before.
Beyond the ice wall, the horrifying truth about the third species is finally uncovered and answers revealed that affect both hunter and Neanderthal alike resulting in a bloody confrontation, the outcome of which has the potential to affect the very future of humanity