Boom!

Boom! Is a roller-coaster read with spaceships, spies and mortal danger! Jim and his best friend Charlie weren't looking for adventure, when they decided to bug the staffroom...But then they overhear their teachers speaking in a secret language and it's too late to turn back. And now they have to explain to the police, the headmistress and their parents where they've been for a whole week - without mentioning the aliens.