Arnold finds out that several athletes at school are using anabolic steroids, so he goes undercover to expose the full story.
Willis gets the sister of one of his old girlfriends to go out with Arnold by giving her concert tickets. When Arnold finds out he is angry at what Willis did, but turns out the girl likes Arnold for real.
Sam gets into a fight at Hamburger Hanger with a kid who constantly picks on him. Sam later discovers the bully is a foster child and is very jealous of what Sam has.
Arnold enlists a hustler to help him conceal a poor grade from Drummond, but the ruse becomes increasingly tricky to maintain.
Sam begins to hang out with Willis a lot more than with Arnold, making Arnold feel left out.
Sam manages to get a popular children's show host for his birthday party, but is disappointed when his friends are more interested in the guest than in him.
Arnold tells his friends that he has had sex with a girl, which leads to her deciding to have sex for real - which Arnold isn't ready for.
Arnold tries to learn the saxophone to impress a girl, but is so bad that his friends try to kick him out of their group.
Kareem Abdul-Jabbar returns as Arnold's teacher and has Arnold take over teaching the class for one day. Arnold isn't thrilled about the assignment at first, but after reading the assigned book, he gets excited.
Arnold hopes to become a photojournalist and ends up getting a job at a newspaper, but he becomes disillusioned when he's asked to run errands instead of taking pictures.
Willis has a hard time adjusting to college, so he decides to drop out. However, he changes his mind when he finds out he's not the only one having trouble adjusting.
Mr. Drummond and Maggie are too busy to spend time together, which has Sam worried that their marriage may be in trouble. So he and Arnold put together a romantic evening for the two of them.
Conclusion. Sam manages to call home and tell Arnold where he is.
Arnold is mugged on his way home from school, and is so traumatized that he begins carrying a knife. In order to get him to open up about the incident, Mr. Drummond arranges for a crime-prevention demonstration at school.
Arnold enjoys going out with a classmate, but his friends think she isn't good enough for him and get him to dump her for a pretty cheerleader.
Mr. Drummond takes Sam and Arnold camping, but is unable to compete with Sam's more-experienced dad.
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