See How They Run (creatures) By Louise Cooper

Everything's just a bit strange at Jon's new house. There's his new neighbour, Frankie. He seems nice enough, but why does he keep twitching in that weird way, and scrabbling about in the yard at night? There's Jon's cat, Gnasher. He's normally so friendly - but he won't go within a mile of Frankie. And then there's the rats - the rats Gnasher keeps killing and leaving Jon to get rid of. The rats that just won't stay buried...