It is loosely based on the book of the same name by David Saperstein.
Aliens who once settled Earth have returned to collect several "Cocoons" that were left behind. Their intentions are to complete their mission disguised as humans. But, when a group of elderly people are accidently rejuvenated by their life force technology, calamaties and romance ensue.
Biological rejuvenation is the key transhumanist element to the movie. The elderly characters are rejuvenated by a science fantasy element known as "life force" which is what gives the aliens their immortality. One of the characters who also had cancer was cured because of the life force and its rejuvenation properties.
There are also some space travel/colonisation elements to the movie.
In 1988, a sequel titled; "Cocoon 2: The Return" was released that followed on from the events in the first movie.
In her presentation to SENS6 in September 2013, Mair Underwood of the University of Queensland singled out the Cocoon films as providing a refreshingly positive assessment of life extension, in comparison to typical Hollywood tropes.