The episode starts off with the gang all trying to find dates for the Senior Prom while Jessie is having a hard time actually selling tickets to the prom because of them being overpriced. Screech on the other hand is selling tickets left and right but the only downside is that the tickets hes selling are for the play Oklahoma and hes charging 50 cents per ticket. The next scene is the gang at The Max and Zack spotting a girl that hes about to ask to go to the prom with. On his way to her table to ask her he briefly sees Kelly saying hi to him and seeing her changes his mind at the last minute which causes him to straight up embarass the girl. Its at that point that he realizes that Kelly is the only girl he can see himself going to the prom with. He gets up the courage and asks her to go with him. Unfortunately a guy named Matt Wilson had already asked her and after an awkward moment of silence they part ways with Zack upset.
Later that day Zack visits good ole Matt at The Max and makes up lies about how Kellys father and brothers are really intimidating and that theyd kick his ass if Kelly is late getting home from the prom among other things which freaks Matt out. He breaks things off with Kelly and theres Zack "convienently" coming to the rescue and getting his wish of them two going together. Meanwhile the prom still might not happen due to low ticket sales so the gang comes up with an idea to save money which in turn will lower ticket sales. Since the gym is already set up for the play Oklahoma they decide to make it a country-themed prom complete with full country gear and music. The idea gets the green light and the prom is on,
Fast foward to the night of the prom. Through a bad coincidence Kelly finds out that Zack set up Matt breaking his date off with Kelly and she peaces Zack out for the prom. Zack tries numerous times to talk to Kelly throughout the prom but it goes through one ear and out the other. Oh yea and Slater and Jessie go down to the boiler room to check on something a few hours before the prom starts and end up getting locked in for the duration of the prom. When Zack finally gets his chance to explain to Kelly why he did what he did (saying shes the only girl for him no matter what) she smiles and believes him and they share a hug. Meanwhile Slater and Jessie hear them talking through a vent and it gets their attention. They go down and unlock them out of the room. Although they were dirty and disgusting they were still happy to catch their last dance at Bayside ever and they share the dance together along with Zack and Kelly as the episode ends.
Prom episodes are always tricky but SBTB always manages to pull the right strings when it comes to their prom episodes. The Jessie/Slater getting locked in the boiler room angel was brilliant because it let them work out their frustrations with each of them knowing that there was no way out of the room. Also the Zack/Kelly dynamic that has become a staple of the show showed its true colors throughout this episode. First with Zack going through the trouble of lying to Matt to get Kelly as his date. Second with them being able to talk through the problems they had and because of the long history they had together, was easy to forgive and enjoy their last prom ever.