A high-school biology teacher looks to become a successful mixed martial arts fighter in an effort to raise money to prevent extracurricular activities from being axed at his cash-strapped school.
Back in his prime, Scott Voss (Kevin James) was a collegiate wrestler with some fairly impressive moves. Now, at 42, he teaches biology at troubled Wilkinson High School. Mr. Voss has begun to grow deeply indifferent in his role as an educator when a troubling announcement stirs him to action. Effective immediately, Wilkinson High will be eliminating all extracurricular activities. Suddenly, the most apathetic teacher on the staff has a reason to get involved. But how is a typical high-school teacher like Mr. Voss supposed to raise the $48,000 needed to save the music program from going belly up? Upon learning that some MMA fighters earn $10,000 just for stepping into the ring, Mr. Voss vows to get back in shape, and subject himself to a series of brutal beatings so his students won't have to go without.
Former collegiate wrestler Scott Voss (Kevin James) is a 42-year-old bored and disillusioned biology teacher at the failing Wilkinson High School. Scott is frequently late to his class, causing Principal Duke Betcher (Greg Germann) to dock his vacation pay. Scott discourages his students from going deep into the subject or even asking doubts or questions during class.Budget cutbacks at the school jeopardize the continuation of its music program, which would result in its teacher, Marty Streb (Henry Winkler), being laid off. Unlike Scott, Marty is a great teacher and really passionate about his subject as well as his students. Plus, Marty's 48-year-old wife Mollie (Nikki Tyler-Flynn) has a baby on the way, and he really needs the money.Duke retains the school football team as that alone accounts for 1/3rd of school's charitable donations.
Concerned for both his colleague and his students, Scott attempts to raise the $48,000 necessary to keep the music program alive. Scott has till end of the school year to bring in the money.Scott checks with his brother Eric (Gary Valentine) for a possible extra shift in the construction sector. But Eric says that nobody is hiring. Eric is married to Lauren (Melissa Peterman), who keeps a tight control on all the money in the house.
At first, he works as a night instructor for a citizenship class. One of his students, Niko (Bas Rutten), approaches him to get some outside tutoring and Scott reluctantly agrees. Niko says that if he fails the test he will be sent back to Holland and things are just starting to happen for him in the USA.When Scott arrives at Niko's apartment, he realizes that Niko was a former mixed martial arts (MMA) fighter.
While watching the UFC at Niko's apartment, Scott learns that the winner of the fight receives $50,000 (and the loser receives $10,000), which gives him the idea of raising the money by fighting in MMA himself. Niko is not convinced as he believes Scott is too old and has no experience, but eventually agrees when he sees that Scott is committed to his goal.
Scott, helped by Niko and Marty, begins with small unsanctioned bouts paying only $750 to the loser. Marty composes intimidating music for Scott to scare his opponents even before the fight begins. Scott nixes the idea and picks his own song "Here comes the boom". Scott starts depositing his earnings with Vice Principal Elkins. One of his opponents goes first and uses Scott's song, forcing him to revert to Marty's song for his entry into the arena.
After Scott knocks out opponent "Lucky" Patrick Murray (Jason Miller) and realizes that wins give larger payouts, needing fewer fights to achieve his goal.Niko begins training him defense, and later brings him to another trainer, Mark (Mark DellaGrotte), to train for offense.Scott is hailed as a hero in school for trying to save Marty's job.
While Mark trains with Scott, Malia De La Cruz (Charice Pempengco), one of Scott's students and a band member, helps Niko study for his citizenship test by putting the information he needs to learn into songs (making it easier for him to memorize). Scott then begins fighting in small MMA fights and gradually gaining higher amounts of money for the school.
Scott eventually gets a dinner date with the school nurse, Bella (Salma Hayek), and they share many moments together showing much affection for each other, while Scott's passion for teaching is rekindled.Mark meets with Scott and tells him that he was offered a fight in the UFC, with the certainty of earning $10,000 even if he loses, but it was denied by Niko. When Scott angrily confronts Niko, Niko apologizes and that the only reason he turned it down was because he was jealous. Niko himself was asked to fight at the UFC and eagerly accepted, but while he was training, he injured his neck and his career ended. Scott and Niko accept the offer.
Scott and his crew travel to the MGM Grand Las Vegas for the UFC event. Once he arrives, he learns that the administrator vice principal Robert Elkins (Mookie Barker) entrusted with the musical program funds has been embezzling both from the winnings and the school, meaning all his effort so far has been lost. Knowing he can get $50,000 if he wins the fight, he attempts to win rather than lose and earn the $10,000.
The publicity of Scott's slow rise to fame has grown, and the school has come to support him. The musical program plays his representative song, and Marty reminds Scott that even if he does not win, he has inspired the students, which is their real purpose. Scott at first is no competition to his dangerous opponent, Ken Dietrich (Krzysztof Soszynski), who is angered that his original opponent canceled and that he is stuck with a man that "does not deserve" to be at the UFC fight.After finding inspiration from the students after being disoriented, Scott manages to win the UFC fight, earning $50,000 for his victory and Dietrich's respect. Scott and Bella kiss through the chain link fence of the octagon.
A side plot involves student Malia, her father (Reggie Lee), and Scott's brother Eric (Kevin James' brother, Gary Valentine), who is unhappily self-employed as a house painter. Eric has a large family and both he and his wife have low paying jobs; Eric enjoys cooking. Malia's father has a restaurant that is failing since his chef quit. Malia's father wants her to stop music and focus less on school so that she can help with the restaurant, but she has a passion for music.
Scott encourages Malia to pursue her musical talent, which drives hostility from her father to Scott for "causing his daughter to disobey him". Eric becomes the chef for her father's restaurant, which improves the business, so Malia's father is thankful to Scott. Once Malia sings at the UFC fight to represent Scott on TV, her father realizes that music is her true passion and is proud of her.
In the closing scene, Niko and all of the students in Scott's citizenship class are awarded American citizenship at the citizenship ceremony.
