20 Million Miles to Earth is a science fiction, adventure story of the first manned space flight and exploration of Venus. When the space craft returns to Earth, it crashes into the sea and kills all onboard except for one astronaut, Colonel Calder (William Hopper). When they explore the wrecked space craft an alien creature is discovered. The creature, classified as an Ymir begins to grow rapidly and soon it becomes apparent that the alien specimen poses a serious threatens to the city of Rome and possibly mankind. Will the authorities be able to stop the creature in time before it demolishes the city or will the alien life form prevail? This is the question at the heart of this terrifying sci-fi adventure.