David is a transfer student to Malibu Central High School. Upon arriving, he sees three bullies, named Bruce, Craig, and Paul, who order Spoony, a semi-skinhead and radical, to wash off a swastika he painted on his locker. The bullies inform Spoony that no forms of protest are permitted at Central High. Soon afterward, David meets Mark, an old friend who he once helped out of a jam at their previous school in Los Angeles. Mark tells David that the school can be like a country club for him if he becomes friends with Bruce, Craig, and Paul, the bullies who rule the school student body and are from wealthy and powerful backgrounds.Over the next few days, David becomes more and more alienated by the abrasive trio as he watches their daily routine. During gym class, they mock the slow-witted, fat Oscar who is unable to keep up with the other students. Later in the locker room, they hit Oscar with towels. David, at Mark's insistence, does not intervene.In the school library, the bullies taunt Arthur, the nerdish student librarian, and dump books all over him. David helps Arthur up after the bullies leave and offers his help to take them on. But Arthur tells David to stay out of it for he says, "we fight and lose our own battles". Later that day, David also witnesses the bullies wreck poor Rodney's car after he parks in their place in the school parking lot. David offers to help Rodney fix his car. Rodney agrees, but again tells David to stay out of Bruce, Craig, and Paul's path for he doesn't want them to be his enemies. Meanwhile, Mark meets with Bruce, Craig, and Paul in Paul's van after school where he tells them about David. But to Mark's worry, the three bullies tell him that they do not want to be friends with David and they do not want to associate themselves, nor interact and nor want anything to do with David. Mark tries to tell them that David is a good guy who can be a great friend and ally to them, but the bullies tell Mark that David looks like a trouble maker. They sternly warn Mark to tell David to stay out of their path. Mark begins to worry about his friend, but he tells the bullies that he will straighten David out.David's only other friend at the school is Teresa, who happens to be Mark's girlfriend. After Teresa and Mark quarrel over David hanging around her, she walks away wanting some space. After classes are let out for the day, the bullies spot Spoony's two girlfriends, Mary and Jane, and decide to rape them just for kicks. When Teresa catches them trying to assault the two girls, they spot her and throw her into a vacant classroom. David sees this and charges into the classroom. He single handedly beats up all three bullies before the rapes are accomplished. While Teresa is grateful to David for saving her, Mary and Jane do not thank him and tell David that he is now a marked man having crossed Craig, Bruce, and Paul.Humiliated by this latest encounter with David, the bullies approach Mark and tell him that he only has one more chance to talk to David to mind his own business. At nightfall, they drive down the Pacific Coast Highway where they find David's car. Venturing down to the beach to find David, Mark sees him with Teresa skinny dipping in the ocean. Filled with anger and jealousy, Mark goes back to the bullies in Paul's van and lies to them by saying that he tried to talk to David, but he wouldn't listen. The three bullies decide to take matters into their own hands.One evening, David is repairing Rodney's car when the bullies appear and kick the jack out and it lands on top of David, in which one of the wheels crushes his left leg. After several weeks in the hospital, David returns to school, now limping from a leg cast under trousers. But worse for David, he can no longer jog which is the one outlet for his anger. Most of the students avoid and snub David for attempting to make a stand against the bullies. Arthur tells David a great big "I told you so" about wanting to take on Craig, Bruce, and Paul. Even Mark is mean and nasty towards David for his flirtation with Teresa. When Mark confronts Teresa later and tells her that he saw her and David that night on the beach, she tells him about how David saved her from being raped earlier that day. She also tells Mark that although she really wanted to have sex with David that night on the beach, he refused to make love to her out of loyalty to Mark. Mark feels guilty over it realizing that he inadvertently got back at David for nothing.But David, having turned psychotic from this latest encounter, secretly plots to kill the three bullies in the same manner he believes they tried to kill him: by making it look like an accident. David begins his lethal plan of revenge when he breaks a cable on one hand glider to one of the bullies: Bruce. During the bullies Saturday hand gliding excursion, Bruce loses control of his hand glider when the cord for the steering breaks, and it rams into power lines, electrocuting him.Craig is the next victim when David intercepts a letter from the janitor to Craig about the school swimming pool being cleaned. That evening, Craig, a championship swimmer in training for the next Olympics, arrives at the school for his private practice sessions when David turns out the lights to the pool area. He tricks Craig into diving into the empty swimming pool.Paul is the final victim when David attacks him the following day in his van and rolls it down a cliff where it hits the rocks and explodes, killing Paul instantly. Mark arrives on the scene and discovers that David is responsible for Paul's death as well as Craig's and Bruce's as well. David challenges Mark to stop him, but Mark loves David too much to fight him. David, however, despite knowing that Mark knows the truth, agrees to let him live out of his love for Teresa.For a time, everyone at the school is grateful to David and is on friendly terms now that the three bullies are gone from their lives. But soon, they all tries to enlist the help of their hero and savior David so they can obtain power. From Arthur taking charge of the geeks, Oscar with the fat guys, to Rodney with the jocks, and Spoony with the punks, they take on one another for power. Soon, fights and arguments break out all over the school as Oscar, Arthur, Rodney, and Spoony quarrel with one another over territory rights. David, disgusted at the fighting and that the oppressed have become the new oppressors, plots to get rid of all the students.A few days later, David commences "the massacre at central high". Arthur is killed when David switches his hearing aid with another one that produces high decibel sonic pulses, which blow Arthurs eardrums out. Oscar is next when he opens his locker and a pipe bomb that David had placed earlier, explodes, killing him and several of his fat boy members. The students panic as more pipe bombs go off, killing and wounded many students. Rodney attempts to flee from the chaos in the parking lot by getting into his car and upon starting it, it explodes, killing him and a number of other jocks and other students with him. Only Spoony manages to escape and hides out in the wilderness with his two girlfriends, Mary and Jane. But David follows them and kills them as well by blowing up a face of a cliff and crushing the three of them in their tent under an avalanche of rocks.Mark, aware that David is behind all the carnage, tells Teresa that they must try to stop David before he kills more people for he has clearly been driven to the edge by everything that has happened. Mark gets a gun and with Teresa they go after David. They arrive at David's house and confront him in his workshop where he is constructing more pipe bombs. David challenges Mark to shoot him and put and end to his killing spree that he is now addicted to since he cannot jog anymore. But Mark can't do it. David then subdues Mark and locks him and Teresa in his workshop and goes to the school, where a student-alumni dance is taking place. David hides a large bomb in the basement of the school and plots to blow up the dance with all the remaining students and teachers inside the gym.Mark and Teresa manage to break out of David's workshop room and head over to the school. Realizing that the only way to stop David is by playing on his last sympathies he has towards them, they enter the gym where they party is being held and begin to dance. David sees them and tries to get them to leave the building before the bomb goes off. The refuse and dance, saying that if David really wants to kill everyone in the school, he will have to kill them too. Realizing that they will not leave and that both Mark and Teresa are sorrowfully willing to sacrifice their lives for him, David rushes (not very fast because of his limp) to the basement and retrieves the bomb. He takes it outside where it explodes killing him, and blasting out all the windows in the school and gym. Mark and Teresa agree to tell the police that the missing Spoony had planted the bomb and that David had given his life to save everyone.