A friendly troll with a magic green thumb grows one flower too many for the queen, whose laws require all trolls to be mean ugly and scare humans whenever possible. As a punishment, he is exiled to a world of concrete, where he should live a life of proper trolldom: Manhattan.

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 them eager to try another home out in the west, where they are promised that mice and cats live in peace. Unfortunately, the one making this claim is an oily con artist named Cat R. Waul who is intent on his own sinister plan. Unaware of this, the Mousekewitz's begin their journey west, while their true cat friend, Tiger, follows intent on following his girlfriend gone in the same direction.