Catherine, Sophia and Nathan make their way to London, accompanied by Victor, a survivor encountered by chance. Along the way, the dangers multiply. Sacha's feelings towards Emily intensify and the young man's behavior becomes more and more disturbing. Feeling threatened, Bill is forced to flee.
When astronomers detect a transmission from another galaxy, it is definitive proof of intelligent extra-terrestrial life. Earth's population waits for further contact with bated breath, but does not have to wait long. Within days, mankind is all but wiped out, with just pockets of humanity are left in an eerily deserted world. As alien ships appear in the sky, the survivors ask a burning question - who are these attackers and why are they hell-bent on our destruction?