There can be no victory without annihilation.

A lull in the onslaught of infected breeds a false sense of security for Johnson and his expanded group. Once again, events unfolding far beyond their knowledge conspire to bring a new type of terror to the survivors.

Others, displaced from what had been their place of safety, struggle to survive against age-old enemies: cold and hunger. In a bold move, they break out, only to make unexpected discoveries which could spell a chance for them to survive.

In a bid to undo all progress, the untested serum is deployed on a massive scale which tips the scales steeply against humanity's chances to win. To live. To remain the dominant species on Earth.

Fleeing the seemingly unstoppable enemy, they pin their hopes on a final attempt for freedom, but that means they must turn their backs on their home forever.