Arnold and Dudley give into peer pressure and experiment with smoking. They realize they don't like the effects of cigarettes, but the real persuasion to have them kick the habit comes from someone very close to home from Dudley - his father, whom despite having had a lung operation, is still a chronic smoker.
After an unfavorable first encounter with a local fitness host named Maggie McKinney, Drummond still decides to invest in her business. He soon realizes that he wants it to be more than a business venture.
Drummond has warned his children on the dangers of hitchhiking. Despite this, Arnold and Kimberly decide to thumb a ride when they find themselves short on cash (instead of swallowing some pride and calling home to get picked up). A seemingly friendly man named Bill decides to give them a ride, but when he makes a "wrong turn," he shows his true colors and forces them to go to his house, where he holds them captive.
As a very worried Drummond wonders where Arnold and Kimberly are, the two are held captive by a schizophrenic man named Bill, who is determined to seduce Kimberly. Arnold (who has been drugged) manages to escape and finds his way home, but Drummond and the others find themselves in a race against time trying to get the details out of Arnold before Bill can attack Kimberly.
Drummond proposes marriage to Maggie, only to find out that she has a 7-year old son named Sam. Everyone is excited about the prospect of having new family members except for Arnold who feels that he will be neglected.
As part of Kathy's wheelchair games, Arnold decides to host a fund-raising party. He gets stuck with Lisa as a date and bribes Robby to take Kathy. He faces a problem when Maggie throws away his old sneakers which contain the donated money.
In order to impress a girl, Arnold becomes the ringleader of a student strike formed to protest the new school dress code. However, things take a turn for the worse when he is the only one suspended from school.
When Sam gets bullied by the Gooch at his school, Arnold tries to stand up to him but is unsuccessful. So he decides to get the new Italian exchange student to fight the Gooch in exchange for the promise of a date with the unsuspecting Willis.
Willis paralyzed friend, Stuart, who was once a terrific gymnast, comes home to visit. Drummond and Willis surprise him by naming a gymnasium after him and inviting the US Olympic Gymnastics team to the ceremony. However, Stuart makes it known that he is fed up with everyone's charity.