Five years after they left, the Antareans return to Earth to rescue the cocoons that were left behind. Before they can be retrieved, one of the cocoons is discovered by a science research team and taken to a secure laboratory for testing. The aliens and their human allies must find a way to retrieve the cocoon in time for their rendezvous with the rescue ship, while the humans travelling with them must decide whether to return to Antarea or stay on Earth and become mortal again.