Ben Healy and his social climbing wife Flo adopt fun-loving seven year old Junior. But they soon discover he's a little monster as he turns a camping trip, a birthday party and even a baseball game into comic nightmares.

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.

When an alien race and factions within Starfleet attempt to take over a planet that has "regenerative" properties, it falls upon Captain Picard and the crew of the Enterprise to defend the planet's people as well as the very ideals upon which the Federation itself was founded.

A young mouse named Fievel and his family decide to migrate to America, a "land without cats," at the turn of the 20th century. But somehow, Fievel ends up in the New World alone and must fend off not only the felines he never thought he'd have to deal with again but also the loneliness of being away from home.