Oswald “Ozzie” Paxton (Vincent Kartheiser) is a computer engineering prodigy and expert hacker whose actions often have his father Jake (Matt Craven) threatening to send him to military school if he doesn’t shape up. One day, he begins an unauthorized download of a soon-to-be-released movie. His download is interrupted when his younger stepsister Melissa Randall (Katie Stuart) enters his room without permission. The resulting squabble between them results in Jake and Melissa’s mother Helen (Annabelle Gurwitch) intervening. In the process, Jake discovers the illicit download and Helen punishes Ozzie, making him take Melissa to her private school Shady Glen.
He takes her there by skateboard where they run into Principal Claire Maloney (Brenda Fricker) and security consultant Rafe Bentley (Patrick Stewart) where it was revealed that Maloney previously expelled Ozzie which she explained to Bentley why security measures were taken after the “science room burnout” that Ozzie caused. Before he can get out of the school, Bentley and his crew of “security guards” use a variety of firearms and tranquilizer dart guns to subdue several staff members, lock down the school, and hold the children hostage. Bentley has planned stages of a ransom scheme involving their parents’ corporations. Ozzie attempts to alert Melissa to the danger. She does not believe him and he is subsequently chased by one of the gunmen. Using a bunsen burner and a vial of acid, he is able to subdue his pursuer. He subsequently begins wreaking havoc with Bentley’s computerized security system.
The police make several attempts to breach the school’s perimeter only to run into automatic gunfire, rocket launchers, and mines. As a concession, Bentley releases most of the children, but keeps the ten richest like Melissa and demands a very large ransom for their return. Ozzie locates ten of the eleven children and rescues them, but Melissa has been taken by Bentley. He then places an improvised time bomb at the bottom of the school’s indoor pool. He attempts to stop the ransom payment, but finds out too late that the man designated to deliver it named Foster Doroy (Michael McRae) was actually Bentley’s confederate. Bentley ties Ozzie to a chair and leaves with his men, keeping Melissa as an insurance policy. They intend to escape through the sewer pipes using ATV’s.
While Ozzie is struggling to free himself, the bomb explodes, flooding the school’s lower levels and neutralizing nearly everyone there. Ozzie and his friend K-Dog (Jon Abrahams) seize an abandoned ATV and pursue Bentley. They rescue Melissa, but Bentley escapes with the ransom. However, Ozzie is able to blow the whistle on Deroy with a little help from Maloney who also witnessed Rafe’s actions. Through his cellphone, the police trace Rafe’s employer to the CEO of a rival corporation named Larry Millard (Jim Byrnes), who masterminded the plot so that the money used for the bidding would be given to terrorists so he could win a bidding war against the corporation run by Miles Lawrence (Bradley Whitford) that is employing Jake.
Soon afterward, Bentley sees a light at the end of the tunnel only to discover that the light leads to a sewage reclamation plant. The money begins to sink into the sewage as police officers arrive to arrest him.