An Ice Age is dawning on Mica's homeland. The climate is getting colder, there are fewer mammoths to hunt, and the future of her people looks uncertain ... Mica's mind is bursting with new ideas to help them survive the long winter, but the others refuse to listen. Shunned and frustrated, Mica feels as if no one will ever understand her. One night, Mica wakes to hear mysterious voices calling. Their cries fill her with a deep longing that she can't explain. But who do they belong to? And then she makes a discovery so incredible, so extraordinary, it will challenge everything she thought she knew about her world ...