At a laboratory in Germany, a researcher sits stunned. Surely it can’t be true? It looks like something scientists thought they would never find. But there’s no mistake here: this girl was born from two entirely different human species. Once the startled experts uncovered the true significance of the unsettling discovery, they realized there was no going back. The mysterious girl, and our own forgotten past, would never be the same.

The chances of uncovering proof of this? Slim at best, or so the experts thought. Then researchers in a cave in Siberia stumbled upon a tiny fragment of bone. Initially, the team didn’t even realize that this came from a hominin – a term that just means “all the species regarded as human.” But soon an incredible story began to unfold.