夜色中,天空突然出现异像,来自太空的神秘光芒消失于大海深处……在一所老人院里,乔(休姆·克罗宁 Hume Cronyn 饰)和一班老人在生命衰竭的阴影中尽量享受人生的快乐,去隔壁的游泳池中戏水是这些老朋友的兴趣所在。与此同时,经营游船出租的杰克(斯蒂夫·古根伯格 Steve Guttenberg 饰)接待了一批客人,这伙人自称他们租船是为了研究海中的大牡蛎,并将打捞来的“牡蛎”放置在老人院隔壁的泳池中。老人们如常在泳池戏水,但是在这里多了几个“巨蛋”以后,老人们从水中得到了源源不断的能量,焕发了青春活力。而在船上的杰克意外发现,他的客人们根本不是研究人员,而是寻找“牡蛎”形状同胞的外星来客……A group of aliens return to earth to retrieve cocoons containing the people they'd left behind from an earlier trip. These cocoons had been resting at the bottom of the ocean. Once retrieved, they stored these recovered cocoons in the swimming pool of a house they'd rented in a small Florida town. Their mission is hampered by a number of elderly people from a nearby retirement community who had been secretly using the pool, and who discover unusual powers from within these cocoons.