We first see Pete walking into a small convenience store and robbing it. Pete has been living from day to day with no direction. He orders a breakfast from McDonald's and eats it in his car, which he has been living out of for some time.
He drives a few miles away to pick up Jennifer and drive her to school. Unfortunately, the previous night, Jennifer had a big fight with her parents about whether or not she wants to go to college. She vows to Pete that she has no intention of going back home. She would rather say good-bye to her friends at school and then go someplace--anyplace--away from Fairlawn and its rows of houses that she refers to as "overturned boxes."
The two drive to a small store, as Jennifer has not eaten yet, and Pete robs it while she is waiting in the car. Jennifer knows that Pete has committed these small crimes in the past, but lately he has told her that he is "starting fresh" and she believes him.
There is a lot of commotion at the high school as the first day of classes brings about some confusion. Pete tells Jennifer that he will meet her in a few hours, toward lunch time. He wants to say good-bye to some of his friends at the mall when it opens.
But Pete never drives to the mall; he leaves his car parked in the student lot. Shortly after Jennifer walks into the school, Pete also enters. He can still pass as a high school student. He walks into what turns out to be an American Literature class and takes a seat. The school day begins. Shortly after listening to the teacher, Mr. Douglass, explain what he expects to accomplish during the semester, Pete suddenly gets up and pulls out a gun.
"It's a very simple procedure," he explains. He instructs all of the students, about thirty of them, to take out their money and pass it up to the first person in each row. He then has Mr. Douglass collect the money in the same manner that he would collect tests, taking from the first person in each row.
At the end of this robbery, Pete simply sits back down in his seat. "What do you want me to do now?" Mr. Douglass asks. "Teach," Pete tells him. He is forced to do just that until the end of the period, at which time Pete blocks everyone into a far corner of the classroom with all the desks and chairs. He has waited for the period to end so that it is possible to leave the room and flow right back into the crowds again. There are over 2500 students in the school; for the time being, it seems that Pete has pulled off a perfect little heist, and that he will simply leave the school grounds.
Soon enough, the frustrated teacher rushes to the main office, which is loaded with students complaining about schedule problems. He manages to get to Mr. Fairleigh, the principal of Fairlawn High, who listens to his story and is shocked. The local police are called.
Oddly, Pete has not left the premises and is actually just sitting and looking at magazines in the school library. In the meantime, Jennifer has met a few of her girlfriends and does not mention that she and Pete intend to leave the area altogether. She is very confused, torn about whether to stay in school and finish her senior year, or to run away.
Soon a police officer named Jensen arrives at the school, and begins to fill out a report about the classroom crime. The officer asks the principal what the instigator looked like. "He looked like..... a senior," he is told.
Principal Fairleigh contemplates evacuating the school. Officer Jensen says to wait while he patrols the halls a while. He peeks in a few classes while thinking that the robber has left the school grounds.
The students in the main office as well as the secretaries had taken notice of Mr. Douglass rushing in earlier, and of the officer, and have been passing around their own ideas about exactly what has happened.
During fourth period, Pete meets Jennifer outside at a cafeteria courtyard and the two eat lunch. They complain about the food, as they did when they were still attending the school. A girl who is sitting nearby starts talking to them. She asks Pete if he has heard about a class that had been robbed. A different student says that he heard something about a class that was robbed by two guys with a submachine gun. It is apparent to Pete that rumors have started and already gone out of control. Jennifer realizes what Pete has done and gets very angry with him--but does not leave him.
Pete and Jennifer contemplate going to Florida to try to start life all over again, "without any parents or teachers." Before they leave the school grounds, Jennifer tries to go to the bathroom, but is stopped by a teacher who demands that she get a hall pass. Pete pays a visit to Mr. Garly, his past guidance counselor, who tries to get him to go to college. "It was nice of you to stop in," Mr. Garly says before Pete leaves. "When everybody graduates, they always say `I'll come back and see you' and very few do."
Outside, Pete is approached by Bobby Mercer, a sophomore. Pete was once friends with Bobby's older brother, and Bobby informs Pete that his brother has been attending a very good school. Principal Fairleigh calls a meeting of the main office secretaries. He yells at them because he has noticed them talking about the robbery situation to teachers and students who have walked into the main office throughout the day. A student's father suddenly rushes into the main office, complaining about the fact that the school has not been evacuated yet.
Pete and Jennifer are walking to their car when they hear the fire alarm going off. They casually drive off school grounds, and head for the main drag. Eventually they end up on the New Jersey Turnpike, unsure of where to go next.
Jennifer calls up her mother from a phone on the Turnpike and ends up yelling at her because she tells Jennifer of her dislike for Pete. The two aimlessly drive south.
In the end, Just Another School Day is as much about being out of high school as it is about being in high school. It is a satire about innocence and ambition. Pete and Jennifer are disgusted with "the real world," and take out their anger on a place where they once had better times. Underneath it all, they are both obsessed with the problem of what they will do with their lives. They are most troubled by the knowledge that they don't know what they want to be.
Some of the students come face to face with Pete's classroom crime; others can only decide whether or not to believe the stories that have circulated around the school. During the course of a single school day, Pete and Jennifer's quest for attention and money portray the elements of a tragic, sick joke.