From the moment that Jimbo and his best friend Charlie bug the staff room and overhear two of their teachers speaking to each other in a secret language, they know that nothing is as it seems. But what does "spudvetch" mean, and why do Mr. Kidd's eyes flicker with fluroscent blue light when Charlie says it to him? Perhaps the teachers are bank robbers speaking in code; perhaps they're spies, or aliens. Whatever they are, Jimbo and Charlie know that there is a big adventure on its way: a nuclear-powered, one-hundred-tonne one, with reclining seats and a buffet car. And as it gains speed and begins to spin out of control, it can only end one way — with a BOOM!