 In the midst of the Antartican snowfield, the scientists and workers of a small American research base are shocked when a helicopter begins to circle their camp, chasing and shooting at a dog. When the helicopter is destroyed and the passenger s are killed by accident, the dog is let into the base and the American s begin to wonder what has actually happened. The helicopter is discovered to be of Norweigan make, and probably linked to the Norweigan base not too far from their own. Helicopter pilot J.R MacReady offers to travel to the Norweigan base and find out what has happened. On arrival, he finds that the place has been totally destroyed. He also discovers a mangled body that looks as though it was once that of a person, which he brings back with him to study. It is only then that the clues begin to add up; the dog morphs horribly into a strange creature that attacks the researchers. They manage to fight it off, but the base s doctor has come to a conclusion: an alien with the power to transform and take the appearance of anybody else is amongst them. Who is infected already, and who can be trusted? J.R MacReady sets out to find the answers to exactly that.