One day, when three men from a local retirement village sneak into a swimming pool on the grounds of a deserted estate, they discover what seem to be oversized oyster shells in the water. Suddenly, they feel physically and spiritually rejuvenated, and believe they've found the long elusive Fountain of Youth. Not long after, the retirees meet a man claiming to be an alien, who explains the secret of the pods to them, and agrees to allow them to keep using the pool. The men's newly invigorated behavior causes something of a controversy in the retirement village, however, as residents are forced to choose between a second youth, or accepting the more natural aging process. But when the alien offers the three men and their wives the promise of eternal life, they must make an even tougher choice: leave, and enjoy immortality on an unknown planet or stay and maintain the relationships they have formed during their long years on Earth.

In this sequel to the popular "Cocoon," the retirees who chose to leave Earth return home for a temporary visit with their loved ones while their alien escorts attempt to rescue a cocoon dislodged by a pesky oceanographer. Once again, the old people must debate whether to stay or to go, and consider whether it is better to die surrounded by the people one loves, or live forever, separated from family and friends.