No longer employed at the biscuit factory, Mr Mack is becoming an inventor instead. Unfortunately, he’s also been arrested. There was a small misunderstanding at the bank involving a saw inconveniently shaped like a machine gun. And, just when he needs her most, Mrs Mack has disappeared off to become the first woman to circle the globe without telling anyone. So it’s up to Jimmy, Robbie, Kayla and Rover the jaded wonder-dog to rescue Mr Mack from prison, avoid some nasty orphan catchers and save the world from an army of ill-mannered slugs. Will they succeed? There’s only one way to find out…