One of the guinea-pigs was standing up with his paws on the mesh. His nose was twitching and searching, as if he knew Joe was coming and wanted to meet him. Joe has just moved into the area and he is very glad when a boy in his class offers to sell him a guinea-pig. It seems such a friendly thing to do. But he soon discovers that Bruiser is no friend. Even worse, there is something very strange about Joe's new pet.