Now back in their own bodies, both of them race to the hospital, although Chris takes time to knock out Rick. Chris in Jack's body is on his way to a meeting about his dad becoming Chief of Staff at the hospital, which won't happen now that Jack's boss found out what Chris did with his wife while in Jack's body. It finally works as Jack in Chris' body is running late for a meeting he slips on the wet floor and knocks a woman out of the window at school. Earl explains it can sometimes take a while to work. Trigger's uncle Earl makes it up and they drink it however looking into each other's eyes, does not immediately work. After a few hiccups they finally find the antidote. They finally get in touch with Trigger's uncle Earl, who explains that they can get the antidote if they go on a trip to the desert. He fails to perform at the big relay race, dropping the baton and attempting to dive only to do so before the finish line." He takes his son's girlfriend Laurie to a concert, but does not enjoying himself finding the music too loud. At school, his knowledge of the schoolwork has him shunned by the students, and Rick beats him up because of a misunderstanding. Jack, meanwhile, has problems of his own in Chris' body. He also seconds a motion proposed by his dad's colleague, suggesting that the hospital could treat patients with no insurance in Chris' words, the hospital should "screw the insurance." The next day he gets called in to work at the private hospital where his dad works, and he ends up handing out a bunch of pills to patients while doing rounds. He bumps into his dad's boss's wife while out in a bar, but he doesn't realize who she is. Chris goes to town in his dad's body, using his dad's credit card to shop and party with Trigger along for the ride. Trigger states he will get in contact with his uncle Earl in order to find a way for the two to switch back, but Earl has just left for another trip. As Jack looks into his son's eyes while having a disagreement over a C grade on an important test, the father and son switch bodies. The serum works by someone ingesting it, then the next person that looks into their eyes switches bodies with them. Jack unwittingly puts it in his Bloody Mary. Trigger brought the Brain Transference Serum in a Tabasco sauce bottle, and the Hammond's housekeeper Phyllis finds the bottle and puts it in the food cupboard. Earl had his leg fixed by Native Americans with a body-switching potion called the "Brain-Transference Serum." Trigger shows Chris how the Brain-Transference Serum works by trying it out on Chris' cat and dog, and the pets switch bodies. Chris's friend, Clarence "Trigger" ( Sean Astin), has an uncle Earl who had been bitten by a snake whilst in the desert. He also wants his son to become a doctor as well, but Chris is not interested. His father, Jack (Dudley Moore), is a surgeon and working hard to get a promotion to the position of the chief of staff at his hospital. He likes a girl at school (Laurie) who happens to be dating his rival and bully Rick.
Chris Hammond (Kirk Cameron) is a high school senior.