When Nicky, Eric, and Tony invest their school class money in the stock market, they risk losing all the money and disappointing their friends. Meanwhile, Screech substitutes for a sick Mr. Belding as acting principal.
Katie's use of painkillers in lieu of letting an injury heal may cost Bayside a swim meet win. Meanwhile, Tony buys a fake diamond for Maria but doesn't tell her it's cheap while Screech runs a massage business from Mr. Belding's office.
Maria, Tony, Nicky, and Katie make a video for a prize, but Eric hijacks it to make a music video and bails on a science project with Liz, risking his friendships with the gang. Mr. Belding is in a wheelchair after he sprains his ankle.
The gang enroll in the Palisades Police Academy, but Maria is upset when her father, the captain, won't spend time with her. The boys volunteer for food duty with a battleaxe while Screech accidentally handcuffs himself to Mr. Belding.
At the academy, Liz changes answers on a test for a boy she likes, preventing Eric from getting into the Honor Core. Meanwhile, Tony tries to find out what Maria got him for his birthday while Screech becomes attached to a police dog.
At the mall, Maria and Katie's friendship may be over after Katie reads Maria's journal and finds Maria wrote that Katie is thoughtless. Meanwhile, Mr. Belding and Screech put on a fake grudge match to promote Gadgets and Gizmos.
At the academy, a corrupt sergeant pressures Nicky, Eric, and Katie to hurt Tony in order to win a competition. Meanwhile, Maria and Tony are addicted to junk food while Mr. Belding and Screech enter a chili cook off.
When an earthquake hits the Palisades Mall, Nicky saves a young boy's life, but doesn't feel like a hero afterwards because he was scared. Meanwhile, Maria and Eric search for an escaped macaw that could get Maria fired while Screech decides whether to tell Mr. Belding he damaged an expensive jukebox.
The gang's decision to drink during a party to celebrate the end of the semester could have drastic consequences, especially for Nicky and Katie. Meanwhile, Screech convinces Mr. Belding that Valley students stole his badminton trophy.
The gang's final prom finds things going wrong at every turn and Maria rethinking her relationship with Tony. Meanwhile, Liz goes to the prom with Eric's little brother while Screech mixes up the dosage for Mr. Belding's allergy medicine.
As graduation approaches, Mr. Belding's decision to leave Bayside leaves Screech in disbelief. Meanwhile, Katie can't go to New York with Nicky because she doesn't get a scholarship while Tony and Eric accidentally ruin the gowns.
A crooked auto repair business rips Maria off, putting a ski trip in jeopardy. Meanwhile, Screech goes on strike to demand a raise, leaving the ski trip without a chaperon and causing Eric and Liz to look for a replacement.