From the back cover:
Mrs. Frisby, a widowed mouse with four small children, must move her family to their summer quarters immediately, or face almost certain death. But her youngest son, Timothy, lies ill with pneumonia and must not be moved. Fortunately, she encounters the rats of NIMH, an extraordinary breed of highly intelligent creatures, who come up with a brilliant solution to her dilemma.

RELEASE NOTES:

off to schoolinathome who picked this up from BookRelay

Thanks Karendawn I got this to read w/my kids. I liked it when I was a kid, so I wanted to share it with them.