Two different science missions in space, one to Haley's comet and another to Europa, become one rescue mission as the spaceship Universe travels to the aid of Galaxy, which is marooned on the forbidden and hostile surface of Europa. During this rescue, physical verification confirms that Europa has a huge mountain, Mount Zeus, made out of diamond.

Mount Zeus appears out of nowhere and is inexplicable, until Dr. Rolf van der Berg obtains a 1981 Nature article that postulates an answer. The core of Jupiter is one big diamond. The implosion of Jupiter as it ignites into the small star, Lucifer, pushes the fragmented core into orbit. Mount Zeus is one of these core fragments.

As Universe explores Haley's comet, a terrorist hijacking brings Galaxy to the surface of Europa. Captain Smith of Universe implements an ingenious plan to use the water of the comet to fuel his ship for the rescue mission. Meanwhile, Galaxy bobs among the diverse life forms of the Europan ocean until beaching on an island that the crewmembers and passengers name, Haven. Dr. van der Berg and Chris Floyd, grandson of Dr. Floyd, fly a shuttlecraft to Mount Zeus. From there, they fly to the site of an earlier spaceship wreck, and then to a mysterious igloo village. Not only does Europa have life, but it also supports intelligent life.

Dr. Floyd appears to Chris as an ethereal entity that tells Chris to leave, because the shuttle emits oxygen, which is poisonous in the Europa biosphere. Universe picks up the crew and passengers from Galaxy, and all gather together at the science colony on Ganymede.