Teenager Bobby Keller tells his best friend, “Dinger”, that he is in love with classmate, Lainie Diamond. Dinger warns him to forget about the unavailable girl, who is already dating their mutual friend, Joel. The next day, Bobby tells Dinger about his dream that involved the elderly man they see every day on their way to school. Elsewhere, the elderly man, Coleman Ettinger, tells Gena, his wife of thirty-six years, about his own dream. When Bobby and Dinger take a shortcut through Coleman’s yard to get to school, he yells at the boys for repeatedly ignoring his demands that they not trespass. Coleman’s friend, Ike Baker, tells him to put up a fence to keep the teenagers out. Sometime later, Ike speaks to Coleman on Gena’s behalf, about his new obsession with meditating and studying dreams. Coleman explains that he is conducting a scientific experiment to see if he can enter a dream while fully conscious, in hopes of finding a way to live forever. Coleman asks Gena to meditate with him, and they rekindle their romance under the moonlight. Meanwhile, Lainie Diamond and her boyfriend, Joel, have an argument, and she takes off into the night, crashing her bicycle into Bobby in the darkness of the Ettinger’s lawn. Both teenagers are knocked unconscious by the impact. When Bobby awakens, Coleman has magically transported into the young man’s body, and is alarmed to be surrounded by Dinger and Bobby’s parents. Coleman goes to sleep in hopes of returning to his own body. In his dream, he speaks to the real Bobby who tells him that Gena has also been transported into another body. The old man awakens, still in Bobby’s body, and goes to school dressed in a sport coat and tie. Bobby’s parents, Gus and Kitty Keller, are concerned about their son’s odd behavior. When Coleman sees Lainie in the hallway, he believes Gena has inhabited the young girl’s body. However, when he calls her Gena, Lainie has no idea what he is talking about. Bobby’s girl friend, Shelley, becomes jealous after seeing him speak intimately with Lainie. Later, Coleman visits his friend, Ike Baker, who does not believe he has been transported into Bobby’s body. However, after Coleman reveals secrets from Ike’s past, Ike begins to believe him. At night, Coleman visits Lainie at home and tries to convince her that their bodies have been switched. He takes her to the Ettinger house, where they slow dance. As Lainie falls under his romantic spell, she forces herself to stop before she kisses him. In another dream, Coleman tries to convince Bobby to switch their bodies back, but the young man refuses, saying that living in a dream is better than his waking life, where he is failing school and constantly disappointing his parents. Coleman vows to fix Bobby’s life so he can return to his former self. In the morning, Lainie awakens, confused by having shared Coleman’s dream. Coleman tries to win her over on Bobby’s behalf, and leaves roses in her locker. When Joel asks his advice about Lainie’s growing distance, Coleman accuses Joel of not really caring about her, and tells him to end their relationship. Joel is angered, but quickly forgives his friend when he apologizes. Later, Coleman performs a dance for Lainie and convinces her to have dinner with him. On their date, she begins to fall for him, and they share a kiss. However, when Coleman tells Lainie that the Ettingers switched bodies with them on the night they collided, she accuses him of being crazy. Class bully, Dumas, sees the couple in a deserted parking lot, and he and his friends beat Coleman and vandalize his automobile. After the fight, Coleman takes Lainie home and asks her to try to remember her dream that night. Dinger warns his friend that Joel will be angry when he finds out about his date with Lainie. When Joel visits Lainie, she lies about where she spent the evening. However, she agrees to go to the school dance with Joel and to discuss their problems then. Coleman visits Ike Baker, and shares his plan to repeat the experiment and attempt a return to his own body. In his dream that night, Coleman again speaks to the real Bobby, who continues to refuse to switch back. He sees Gena and Lainie speaking to each other, but cannot get to them in the dream. The next day, he takes Bobby’s Scholastic Aptitude Test (SAT), in hope of getting the young man accepted into college. Afterward, Lainie tells him she dreamt about the Ettingers but is not convinced it means anything. She reveals, however, that in the dream, Gena warned her not to fall asleep or else the Ettingers would be lost forever. Lainie agrees to stay awake all night, and tells Coleman that he should take Shelley to the dance while she goes with Joel. At the dance, Joel arrives intoxicated, and becomes hostile with Lainie. When she ends their relationship, he throws her to the ground, and Coleman comes to her aid, fleeing the dance with her. He takes Lainie to an old-fashioned dinner club full of elderly couples, and dances with her. Afterward, they go to the Ettinger’s front lawn where Coleman teaches her the meditative movements he and Gena were performing that sparked the body switches. Dinger finds them and asks for their help with Joel after learning that their drunken friend has a gun and is on his way to confront class bully, Dumas. As the friends race to stop him, Lainie’s mother finds her with Bobby, whom she does not like, and forces her daughter to come home. Coleman says he will see her later, and Lainie promises not to fall asleep. However, after hearing her vow, her vindictive mother drugs Lainie with a sleeping pill. Meanwhile, Joel threatens Dumas in an alleyway, and Coleman and Dinger arrive to find him pointing a gun at Dumas’s head. Coleman uses words of wisdom to convince Joel to lower his weapon, telling them that in a few years, none of their fights will matter. Joel turns the gun on Coleman before relenting and emptying the bullets from the gun. Elsewhere, Lainie fights to stay awake. When Coleman arrives at her house, Lainie’s mother refuses to let him inside. He climbs the trellis to her bedroom and tries in vain to wake her. Coleman leaves devastated. However, in the morning, the elderly man has returned to his own body, but is convinced he will never see Gena again. When he falls back asleep, Bobby tells Coleman in a dream that he made up the story about losing his wife forever. Coleman awakens to find Gena dancing to rock music in the kitchen, unaware the transformations had occurred. In time, Coleman sees Bobby walking to school with Lainie, and gives him permission to walk through his yard. Bobby respectfully refuses, sharing a knowing look with the old man.