Earth Swarm by Tim Hall
KILLER DRONES ATTACK! Terrifying drones controlled by artificial intelligence are destroying London . . . Genius scientist John Strider helped create the machines - and he's disappeared. Only one person has a chance to stop them - his teenage son, hotshot pilot Hal Strider. Hal and his sister Jess are determined to prove their father's innocence, and to find a way to save the city. But in order to survive, they are going to have to take on a terrible and remorseless foe. THE MACHINES ARE COMING . . .