Boom!: (or 70,000 Light Years)

From the moment that Jim and his best friend Charlie overhear two of their teachers speaking to each other in a secret language, they know there's an adventure on its way. Bur what does 'spudvetch' mean? Perhaps Kidd and Pearce are bank robbers talking in code, or spies, or aliens. Whatever they are, Jimbo and Charlie are determined to find out.