Ever since last summer, Mrs. Frisby has been worried about Timothy, her younger son. Timothy has had pneumonia—he almost died—and now he is too frail and weak to be moved. But if the Frisbys don't move immediately, they'll all be killed!
Mrs. Frisby is frantic. Then she hears about the wonderful Rats of NIMH—rats who are strong, smart, able to do almost anything. They've escaped from the lab at NIMH. They can save the Frisbys. But will they?