Sam wakes to see strange vessels gathered in the skies around London. As he stares up, people stream past, walking silently towards the enormous ships which emit a persistent noise. Only Sam seems immune to the signal.

Six months later, Sam is absolutely alone. In his underground bunker he has food and water for a couple of days. He has no choice but to venture above. Spotted by a flying drone, Sam escapes, but not before the drone slashes him with a barbed tendril. That night, drenched in sweat, Sam realises without medical supplies the wound will kill him. This time above ground he is less lucky. Cornered again, Sam thinks he has reached the end - then the drone is shot down in a hail of machine gun fire.

In five minutes Sam learns two things: he is not alone; the drone injury should have killed him instantly - yet he is still alive. The battle for earth is about to begin.