With an invasion from somewhere from outer space in progress, we humans find ourselves being taken over, one by one, by some form of alien beings. While they invade our planet and take over the minds of everyone they come into contact with a few manage to remain "wild and free". Melanie Stryder, played by Saoirse Ronan (Atonement, The Lovely Bones) attempts to hold out but succumbs to an alien named Wanderer. Wanderer has been warned about possession of human bodies and the consequences involved such as mood changes, vivid memories from that human's past life, and an entire gamut of emotions they have never experienced where they came from. When Melanie refuses to yield her mind to the alien they struggle for what may be the last remaining human being on planet Earth.lso starring William Hurt (The Big Chill, Kiss of the Spider Woman) as Melanie's eccentric uncle Jebediah Stryder, Diane Kruger (National Treasure, Inhale) is one of the mind stealing alien "souls", and Jake Abel (I Am Number Four, The Lovely Bones) is a rebellious human who wants to kill the aliens as quickly as he can find them.