An American reporter is accidentally forced to join a secret team of scientists who got hold of a crashed spaceship from Mars with a creature they dubbed "areanthrop" (Greek: Ares=Mars + anthropos=man) in it. The areanthrop seems to be a kind of cyborg: a sentient protoplasm which in the course of natural evolution built itself a "robotic suit", rather than developing a biological body. Scientists poke, prod and pry it with all means possible in attempts to study it. Eventually the areanthrop gives them a telepathic trip to Mars and seizes control over a member of the team, and after that it is completely destroyed.