In St. Petersburg, Florida, senior citizen Bernie Lefkowitz sits by the grave of his late wife, Rose, saying he is lonely living at the Sunny Groves Rest Home. Elsewhere, teenager David turns off the television. However, it turns itself back on with David’s grandfather, Ben Luckett, onscreen. Ben says that he and David’s grandmother, Mary, are returning to visit Earth after leaving five years ago to live forever on the planet Antarea. David tells his mother, Susan, but she insists his grandparents were lost at sea. While arguing, the doorbell rings. Finding Ben and Mary Luckett at the door, Susan faints. At Sunny Groves, Bernie attempts to hang himself from a light fixture, but the fixture breaks. Hearing a knock at his door, Bernie opens it and is overjoyed to find his friends, Joe Finley, Joe’s wife, Alma, Bess McCarthy, and her husband, Art Selwyn, who left for Antarea with Ben and Mary. The following morning at Capt. Jack’s Glass Bottom Boat Tours and Souvenirs shop, Jack Bonner sees Kitty, an Antarean alien he met five years before. Kitty tells him seismic activity on the ocean floor is disturbing the cocoons containing Antareans previously left on Earth. Jack agrees to help Kitty and her fellow Antareans, Pillsbury and Doc, retrieve the cocoons. At the Sunrise Court motel, Joe and Art meet proprietress Ruby Feinberg. Afterward, Ben arrives in his classic Cadillac. The men come to Sunny Groves to take Bernie to the beach. However, an orderly informs Bernie he cannot leave the premises and tries to push Art out of the way. Art grabs the orderly’s arm and flips him. As Art leaves, residents of Sunny Groves applaud. Meanwhile aboard Jack’s boat, Manta IV, Kitty, Pillsbury and Doc SCUBA dive to retrieve the cocoons. Alone onboard, Jack sees a ship from the St. Petersburg Oceanographic Institute lifting a lone cocoon in a net. Afterward, Jack, Kitty, Pillsbury and Doc break into the Oceanographic Institute to locate the cocoon. Pillsbury sheds his human skin and floats into an air duct in his Antarean form. He finds the cocoon being scanned by scientists Sara, Doug, and Rebecca. As images appear, Sara notices the cocoon contains a humanoid figure. In the evening, Art, Bess, Joe, and Alma take Bernie to a supper club. While dancing, Art sees Ruby Feinberg at the bar, and thinks she would be a good match for Bernie. After Ruby joins the group, Bernie begins to enjoy himself. Liking Bernie, Ruby kisses him. However, Bernie tells her he is a married man, and leaves. The following morning, Alma goes jogging and sees a preschooler crying. Approaching the girl and her teacher, Alma places her hands on the child’s forehead and, with her powerful Antarean life-force, heals her. As the teacher takes the girl to the first aid station, Alma agrees to watch the children, and tells them about Antarea: a far off planet where no one dies or gets sick. At Sunrise Court, Bernie arrives to meet Art and Joe and sees Ruby, who apologizes for kissing him. When Ruby offers to buy him a drink that evening, Bernie declines, but she insists. Afterward, Bernie, Joe, Ben and Art go the park for lunch. While eating, a basketball lands on their food. The young men from the basketball court come to retrieve their ball, but Bernie yells at them. Art suggests a four-against-four basketball game, and Ben wagers that the oldsters will win. The young men accept the bet. As the game progresses, the young men are stunned by the agility of Art, Joe and Ben. After Art slam-dunks the ball, Bernie is passed the ball and scores the winning basket. Elsewhere, Bess faints while shopping with Alma and Mary. At the St. Petersburg General Hospital, Bess’s doctor informs Art that she is six-weeks pregnant. While at the hospital, Joe meets with a doctor about a pain in his side, and is informed that his leukemia has returned. When Joe arrives back at Sunrise Court, Alma tells him she was offered a job at a preschool for foster children. Not wanting to dampen her good mood, Joe does not mention his cancer. At the St. Petersburg Oceanographic Institute, the cocoon is opened, revealing an Antarean alien. Dubbed “Phil,” the alien is moved to an observation room, where he shows signs of reading Sara’s thoughts. Later, Sara demonstrates Phil’s abilities for General Jefferds of the United States Air Force. Jefferds informs her boss, Dr. Baron, that Phil will be transported to a secret location. Sara overhears, and worries for Phil’s safety. Aboard the docked Manta IV, Jack gives Kitty a seashell, and reminds her that during her last visit to Earth, they had a passionate night when they “shared themselves.” Kitty tells Jack she would like to do that again, but he insists they go on a date first. Later at a French restaurant, Kitty becomes highly aroused after taking a bite of her food, and levitates while glowing. The glow leaves her body as a comet and soars throughout the restaurant. As diners run for cover, Jack and Kitty leave. Elsewhere, Ruby and Bernie go to a nightclub. As Bernie dances with Ruby, he kisses her. However, he sees a vision of his dead wife, Rose, and tells Ruby he made a mistake. Ruby tells him he needs to move on. In the morning on Manta IV, Kitty apologizes to Jack for her behavior. Jack suggests that perhaps he is not meant to find love. Wanting to ease his doubt, Kitty lulls Jack into a dream state and shows him his future wife and two daughters. Unable to see the woman’s face, Jack notices a red, heart-shaped birthmark on her neck. Later, Kitty enlists Ben, Mary, Art, Bess, Alma and Joe to rescue Phil before the Antarean ship returns at midnight. Bernie arrives, and overhearing that his friends are leaving again, storms away. Later, Alma goes to the preschool to see the children. While playing, one boy runs into the street. Just before a car strikes him, Alma pushes him and is hit instead. At the hospital, Joe is told Alma is in a coma. To save her, he places his hand over Alma’s heart and gives her his life-force. Alma awakens, and Joe tells her to take the offered job. As they embrace, Joe dies. In the evening, Ben and Mary say good-bye to David, and drive to Sunrise Court to pick up their friends and say good-bye to Bernie. However, Alma plans to remain on Earth. After Ben drives away, Bernie apologizes to Ruby. Bess and Mary board the Manta IV, while Kitty joins Ben and Art in the Cadillac. Following an institute cargo truck to a restaurant parking lot, Ben, Art and Kitty sneak into the truck bed. After the truck leaves, David appears from the Cadillac’s trunk and follows them to the institute. Once inside, Art disguises himself as a security guard, while Kitty reverts to Antarean form. When Ben locates Phil, Art shuts down the lab’s power. In the dark, Ben grabs Phil and hides. As the lights come back on, Sara and her colleagues notice Phil is missing and go searching for him. In the hallway, Art directs them to Antarean Kitty, pretending to be Phil. While the scientists follow her, Ben goes toward the rear door. However, the security gate begins to lower. David finds Ben and helps him stop the closing gate. As Ben and David run outside, Sara tries to stop them. Ben explains Phil needs to return home. Seeing Phil dying, Sara lets them escape. Reaching the shore, Ben and David join Kitty and Art. Jack arrives in an inflatable boat and they head to the Manta IV. After boarding, an Antaraen spaceship appears overhead. Walter, the leader of the past Antarean mission to Earth, materializes in human form. As the Antareans prepare the cocoons, Ben and Mary decide to stay on Earth with David. Art and the pregnant Bess decide to return to Antarea where they will be able to experience their future child growing up. After saying good-bye, the cocoons, Antareans, Art and Bess are teleported to the spaceship, which flies away. Later at the dock, David, Ben and Mary leave as Jack locks up his boat. Sara appears, saying she ran out of gasoline. Jack offers to give her a ride to the gas station. As Sara tells Jack she just quit her job, he notices a red, heart-shaped birthmark on her neck.