Some time after the Mousekewitz's have settled in America, they find that they are still having problems with the threat of cats. That makes the

大地在污染和环境灾害的双重打击下，已经处在崩溃的边缘，为了生存，人们创造了一个与世隔绝的都市，叫做ECOBAN(这个名字由ecology和ban合并起来，意思是“毁灭生态”)，而这个都市完全靠大地的污染物苟延残喘。　　但是，只有极少的经过挑选的人才可以进入这个隔绝的都市，这些人成为城市中的特权阶