Mrs. Frisby and her family live in an adorable overturned cinder block, where they all cozy up together in an adorable pile of fur and whiskers. Their cute house and sweet personalities are all it takes to make sure the reader cares about what will happen to the family in the future. Who doesn't love a talking animal or two?
When Timothy Frisby catches a cold and becomes too ill to move into the family's summerhouse (a must because of the dangers of springtime plowing), Mrs. Frisby seeks help from her neighbors—the rats. The rats at first do not want to help lift tiny Tim and his family out of the depths of anxious despair, but they finally come around, as we hoped they would.
The rats have to work around the clock to get the Frisby household moved, all the while knowing that a mysterious group of exterminators is headed to the farm... to kill them or even to take them back to NIMH. Uh oh. At this moment of crisis, the reader has fingers and toes crossed that it will all work out for both the rats and the Frisbys.
The rats move the house and, owing to some herculean efforts from Justin and Brutus, the rats are able to move onto the next stage of the Plan: World Domination. Wait a second—that's not right. These rats don't want to make us all their minions. They just want to move to Thorn Valley and live off of the land, hippie-style. When all of the characters finally get what they want, readers finally get what they want: the promise of a happy ending.
Though we never see the rats living happily ever after, we have to believe that they escape and make it to Thorn Valley. (Why? Because rats who can read and manipulate electricity can do anything, of course.) The very end of the book has the Frisbys all together in their summer house, with Martin promising to seek out the rats in their new home to thank them for all they have done for his family. Hmmm. Shmoop smells a sequel.