A troubled student named Jill (Kellie Overbey) volunteers to work on a school project with Mike (Kirk Cameron) and Boner (Josh Andrew Koenig). This, however, is a subterfuge: Jill has been contemplating suicide due to some very serious problems at home, and she hopes to get some free counseling from Mike's psychiatrist dad Jason (Alan Thicke). But as it turns out, Jason is presently weighed down with a few self-pity issues of his own.
Luke's father George visits the Seavers hoping that Luke has mellowed a little and would like to spend some time with him but Luke doesn't. He was about to leave when he collapses outside the door. He says that can't move, so they take him in. Jason and Ben offer to deliver his load, and they experience all sorts of chaos on the way. Mike thinks that George is faking his injury so that he could stay and Luke would have to talk to him. But the doctor tells Maggie who tells Mike that unless George stops driving trucks, he could become paralyzed. Mike talks to George and tells him to tell Luke but doesn't want Luke to pity him and doesn't anything else to do but be a trucker. Mike suggests that maybe he could open a truck stop. Luke finds George struggling to get up and they finally talk. The next day after Jason and Ben return, George tells them that he is giving up trucking and will open a truck stop and Luke's going with him. Luke says goodbye to the Seavers.
This movie takes place eight years after the Growing Pains series finale where the Seavers are in their new house. Mike finally married and adopted children, all adopted from countries around the world. Mike is successful in advertising. Carol is a successful lawyer on Wall Street. Ben cleans out swimming pools. And Chrissy is a 17-year-old kid about to graduate from high school with a smoking habit that she stops at the end of the film. Maggie gets fired from her job as a press rep for a senator, and runs against him for the job at her grandchild's suggestion. Carol acts as her campaign manager where she first clashes with, then falls for, the single father running the opponent's campaign, which leads to confusion and chaos.
Now that Seaver children are out of the house, the Seaver parents, Jason and Maggie, attempt to sell their house, because they want to retire. They both have their own idea about what they want to do after the sale; Jason wants to buy an RV and travel the country, but Maggie wants to purchase an Italian villa. Ben is the real estate agent who is closing the sale, much to the delight of his new boss. Mike and Carol, however, are very much against it, and have both returned to the Seaver house, each with issues in their own lives that they are trying to sort out. On top of all this, Chrissy has also returned to the Seaver house, looking for a place to come to after having been evicted from her apartment.