Zack and Slater bring the wrecked car to the auto shop, and Slater figures that it's going to cost about $600 to fix it. Of course, they don't have the money, so Zack comes up with a scheme to make the money. He sells lottery tickets to the students, and in algebra class, the last five digits of the answer will be the winning ticket. Before the lottery starts, though, Screech pulls the fire alarm and switches the teacher's box of numbers with one that Zack has fixed. When the lottery is over, Screech is the winner. Since they fixed the whole thing, Zack and Slater strong arm Screech into giving them the money, and unfortunately for them Eric overhears, and threatens to tell everyone that the lottery was fixed unless Slater gives him his car so he can go to the MC Hammer concert with Lisa. Zack relishes telling him that Lisa only went out with him because he asked her to. Shortly afterwards, Eric confronts Lisa, and she admits everything, so Eric says he never wants to talk to her again. Lisa cries, because it turns out that she really likes him.
At the auto shop class, the teacher sees the car and figures it's part of the class, so they're going to fix the damage. Eric, however, suggests that it would be a good experience if they took apart the whole car. Screech protests, but is overruled. Later, when Zack and Slater return with the parts they bought, they're shocked to see that the car has been completely disassembled.
Later, Jessie confronts Eric about everything he's been pulling, and Eric brags about how he got the class to take apart the car, and therefore won the war against Zack and Slater. She tells him off, because she had been so happy to be getting a brother but instead the whole thing has been a disaster, and he foolishly calls her a "chick," which leads to her punching him out.
Mr. Belding comes back from his conference early, and wants to see his car. Zack and Slater claim that a hurricane hit Bayside and destroyed the car, but Mr. Belding assumes that they're just kidding. When they get to auto shop, Mr. Belding is thrilled to see the car, and Zack and Slater are shocked that the car is put back together perfectly. After Mr. Belding leaves, Eric pops out from under the car and admits that he put the car back together. He then tells them that he doesn't fit in and is returning to New York, and returns the blackmail tapes to them.
As Eric packs to leave, Jessie tells him that she doesn't want him to leave. The rest of the gang shows up and also tells him that they want him to stay, and Lisa admits her feelings for him. Jessie says that she now realizes that a new family like theirs will take more work than she thought, but that it'll be worth it, and she really wants him to stay and be her brother. He agrees, and they embrace.