Stormbreaker Alex Rider, a 14-year old student, lives with his uncle Ian Starbright and Jack Starbright as their housekeeper. Alex is disappointed to learn that Ian is a bank manager. A few days later, Alex is told that his uncle has died in a crash in his car however, he quickly realizes that the man who died was a spy working for MI6 and was killed.
The ex-employers of his uncle’s former employer, Mrs. Jones and Alan Blunt of the Special Operations Division (MI6) Then, they recruit him. They explain to Alex that their uncle been instructing them as spymasters. Alex initially resists cooperating but is eventually persuaded to cooperate after his uncle and Mrs. Jones threaten to halt Jack’s visa renewal as well as deport her. Alex is then taken to a military training camp located in the Brecon Beacons, home to the British Special Air Service. At first his fellow students do not like him due to his age, but soon he earns respect from them due to the abilities he acquired from his unwitting training.
Smithers gadgets assist him on his initial mission. Billionaire Darrius Sayle has donated free high-powered computer systems code called Stormbreaker to every school in the United Kingdom. MI6 is suspicious of his apparent generosity and is sent Alex undercover as a competition winner to conduct an investigation. He is able to meet Sayle as well as his two accomplices Mr. Grin, Nadia Vole and is shown the Stormbreaker computer. While Alex is having dinner with Sayle later the suspect Vole steals Alex’s phone and tracks down the SIM code to his residence in Chelsea. It is at this point that Alex discovers her true identity and fights Jack. Nadia leaves the scene when Jack defeated her, despite being defeated. That night, Alex sneaks out of his bedroom to view an unconfirmed delivery of containers to Sayle’s abode.
Alex is caught and his cover is exposed. After trying to escape the facility, Alex is seized by Sayle. Sayle explains the true reason behind Stormbreaker. Each system contains an altered smallpoxvirus that, if activated in the Stormbreaker releases it will kill all children in the country. Sayle is released and leaves Alex tied up and departs to the London Science Museum. Nadia dropped Alex in a water tank where he’s likely to be killed by the giant Portuguese man of war. However Sayle is able to escape with the iron-disintegrating spotcream supplied by Smithers. Nadia is then subdued by the jellyfish and the tank gets shattered. To gain Mr. Grin’s trust, Alex rides on a Mi-8 helicopter piloted and controlled by Mr. Grin. Alex jumps out of the helicopter and crashes into the ground just as the Prime Minister is about to press the button to activate the computers. Alex shoots the podium with the rifle that leads Sayle to abandon his strategy.
Exhausted, Sayle flees to complete his backup plan. Alex and Sabina Pleasure who is a friend from school, follow Sayle on horseback through London’s streets. At a height of fifty floors on one of Sayle’s skyscrapers, Alex reaches him and unplugs his backup transmitter. Sayle chases him out onto the roof and knocks Alex and Sabina from the top, hanging by a dislodged cable. Then, in a shocking twist, Yassen arrives in a helicopter and shoots Sayle (in the same way as he shot Ian) before rescuing Alex. Yassen tells Alex that Sayle is now an embarrassment to his employer and that Alex must forget about Sayle. However, Alex insists that Ian’s death signifies that they are enemies.
Alex goes back to school. Sabina and he talk about the incident and agree that it should never again happen. The film ends with a person looking at Alex from a distance. This isn’t the end as Alex realizes.