By Anthony Horowitz
A fourteen-year-old learns his dead uncle was a spy, then gets pressured by MI6 into finishing the man's last mission. It's James Bond with a teenage boy in real danger.
Alex Rider is fourteen when two policemen knock to say his uncle Ian died in a car crash. Alex doesn't buy it, and he's right: Ian was a spy, he was murdered on the job, and he'd quietly spent years training Alex for a life he never explained. British intelligence corners Alex, leans on his future to push him into Ian's place, and sends him undercover after Herod Sayle, a billionaire about to give every school in the country a free computer called the Stormbreaker. What Alex finds is a plan to kill thousands of schoolchildren, and he's the only one positioned to stop it before the men hunting him catch up.
It's built for the older child who's outgrown the funny, safe spy stories and wants the real thing: a genuine thriller with a body count, gadgets that actually matter, and a hero in danger from the first chapter. Horowitz writes it like a Bond film. The chapters are short, most of them end on a cliffhanger, and the set pieces move at movie speed, so it reads fast even for a child who usually stalls out partway through a book. There's a long series behind it too, so one who finishes hungry has plenty more lined up.