Mrs. Frisby and the Rats of NIMH by Robert C O'Brien

When widowed Mrs. Frisby's youngest son Timothy comes down with pneumonia, she goes to the area herbalist, Mr. Ages, for medicine which he says will cure the sickness in three or four days. But, he adds, it will be several weeks before Timothy can go out into cold or cool air safely without falling sick again and dying.

This doesn't seem like much of a problem, does it? And it wouldn't be, for you or I. We'd be a little bored, of course, stuck in the house, bundled in blankets, a little tired and weak, but it wouldn't be that big of a thing.

But you see, Mrs. Frisby, Timothy, and the rest of her children are field mice, and even Mr. Ages is a small white mouse. They live in houses they've created on Mr. Fitzgibbon's farm. Mr. Ages lives in a hollowed-out space of a brick wall, and Mrs. Frisby lives with her four children in a concrete block - you know, one of those ones with two holes through the middle, just right to make two cozy rooms for a mouse family? - against a boulder in the middle of Mr. Fitzgibbon's big field.

Which is the biggest problem of all, for you see, every spring when Mr. Fitzgibbon begins to plow his field, Mrs. Frisby and her family have to move to a safe place in the woods. But with Timothy sick, they can't move - and the spring thaw is coming soon. Mr. Fitzgibbon has the tractor ready, with the sharp shiny plow already attached to the back.

They can't go and they can't stay, and perhaps there's only one direction Mrs. Frisby can look for help, if she can find the courage: the mysterious rats of NIMH.