After an asteroid draws an astronaut and his ship to its surface, he is miniaturized by the phantom planet's exotic atmosphere.

Landed on the moon, Capt. John Anderson and his fellow astronauts quickly find their mission threatened – first by the disappearance of two team members, then by a troubling interaction with aliens who appear to be living within the moon itself. The aliens have weapons that could plunge parts of Earth into another ice age, and they're aiming for the United States.