While Dr. Jack Hammond (Dudley Moore) is a respected surgeon on his way to getting a coveted position at the hospital where he works, his son, Chris (Kirk Cameron), is a mediocre high school student with problems his dad could not care less about. Then one day, Chris' friend (Sean Astin) invents a formula that causes father and son to switch minds. Now Chris, who is in Jack's body, has to deal with all the grown-up issues his dad contends with, while Jack gets to revisit the days of teen angst.