Five years after they left, the Antereans 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.
Having returned with the aliens, the elderly couples from the original film face indecision about whether to return to Anterea or stay on Earth and become mortal again. Joe learns that his leukemia has returned, but he knows it will be cured again as soon as he and Alma leave Earth. However, when Alma is hit by a car, Joe gives up the last of his lifeforce to save her. Arthur and Bess learn that Bess is pregnant, and decide to raise the child on Anterea so they will live long enough to see him grow up. Ben and Marilyn decide that being with their families is more important than living forever, so they decide to stay.
The group manages to infiltrate the lab and rescue the captured Anterean. Jack sails them out into the ocean, where the space travellers and the cocoons are picked up by an alien craft. Jack then sees Sara and they walk away from the docks.