The migration of Homo sapiens into Asia is detailed. Recent evidence suggests the exodus from Africa began earlier than thought; and that ancient humans mated with another human species known as the Denisovans.

The final episode explores the arrival of Homo sapiens in prehistoric Europe. The Neanderthals were already present on the continent, and the two species were similar enough to interbreed, but the influx of modern humans had dire consequences for their evolutionary cousins.