When the Viking space capsule suddenly returns to Earth from its long ago trip to Mars, it brings with it an intelligent visitor that is part __QUOTE__Alien__QUOTE__ and part __QUOTE__ET__QUOTE__. Encased in armor, it extends a humanlike form from its shell to examine its surroundings and shows an interest in humans including a soft caress of a female scientist prior to the Army killing it. This only enrages its sibling.