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.

The troopers of two starships have joined forces to terminate a massive bug attack at a Federation outpost. Before the mission can be completed and the survivors evacuated, one ship abruptly departs and goes inexplicably dark. The remaining battle-hardened troopers race to the rescue only to discover that the threat from the bugs is about to hit home.