PJ and Josie are two high school students who have always struggled to fit in with the popular crowd. They constantly feel like outcasts and have never had much luck with girls. One day, while watching a Kung Fu movie, they come up with the idea to start a self-defense club at their school. They figure that if they can teach other students how to defend themselves, they'll become more popular and maybe even get some girls.
At first, the club is a complete failure. Only a few students show up, and they are all social misfits like PJ and Josie. But then something unexpected happens. One of the most popular students in school, a guy named Tyler, shows up to one of their meetings. He tells them that he's been having trouble with a bully and wants to learn how to defend himself. PJ and Josie are thrilled to have a popular student in their club, but they're also a little suspicious. Why would Tyler, who has always been a jock and a ladies' man, suddenly be interested in self-defense?
As it turns out, Tyler's interest in self-defense has less to do with being bullied and more to do with a secret underground fighting club that has been set up in the school. The club is run by a group of seniors who are all former martial arts champions. They've been challenging other students to fights and betting on the outcomes. Tyler joined the club as a way to impress a girl he likes, but he soon realizes that it's much more dangerous than he thought.
PJ and Josie are horrified when they discover the existence of the fighting club. They had no idea that their innocent self-defense club would lead to something like this. They decide to take matters into their own hands and try to shut the fighting club down. But they quickly realize that they're in way over their heads. The seniors who run the club are ruthless and will stop at nothing to protect their secret.
In the end, PJ and Josie are forced to enter the fighting club themselves in order to bring it down. They are pitted against some of the most skilled fighters in the school, including Tyler, who has become addicted to the adrenaline rush of the fights. It's a brutal and bloody battle, but in the end, PJ and Josie emerge victorious.
The fighting club is shut down, and PJ and Josie are hailed as heroes. They even manage to turn their self-defense club into a more legitimate organization, with proper training and safety protocols. And, as a bonus, they finally get some attention from girls. It's a happy ending for everyone except the seniors who used to run the fighting club. They are expelled and forced to face the consequences of their actions.