kids encyclopedia robot

Mrs. Frisby and the Rats of NIMH facts for kids

Kids Encyclopedia Facts
Quick facts for kids
Mrs. Frisby and the Rats of NIMH
Mrs frisby and the rats of nimh.jpg
First edition cover with Bernstein artwork
Author Robert C. O'Brien
Illustrator Zena Bernstein
Series Rats of NIMH
Genre Science fiction, Children, Fantasy novel
Published 1971 Atheneum Books
Media type Print
Pages 233
ISBN 0-689-86220-2 (second Aladdin paperback edition, 1999)
OCLC 52814814
LC Class PZ10.3 O19 Mi
Followed by Racso and the Rats of NIMH 

Mrs. Frisby and the Rats of NIMH is a 1971 children's book by Robert C. O'Brien, with illustrations by Zena Bernstein. The winner of the 1972 Newbery Medal, the story was adapted for film as The Secret of NIMH (1982).

The novel relates the plight of a widowed field mouse, Mrs. Frisby, who seeks the aid of a group of former laboratory rats in rescuing her home from destruction by a farmer's plow, saving her son from pneumonia, and of the history of the rats' escape from the laboratory and development of a literate and technological society.

The work was inspired by the research of John B. Calhoun on mouse and rat population dynamics at the National Institute of Mental Health from the 1940s to the 1960s.

Plot summary

Mrs. Frisby is the head of a family of field mice. Her son Timothy is ill with pneumonia just as the farmer Mr. Fitzgibbon begins preparation for spring plowing in the garden where the Frisby family lives. Normally she would move her family, but Timothy would not survive the cold trip to their summer home. Mrs. Frisby obtains medicine from her friend Mr. Ages, an older white mouse. On the return journey, she saves the life of Jeremy, a young crow, from Dragon, the farmer's cat– the same cat who killed her husband, Jonathan. Jeremy suggests she seek help in moving Timothy from an owl who dwells in the forest. Jeremy flies Mrs. Frisby to the owl's tree, but the owl says he cannot help, until he finds out that she is the widow of Jonathan Frisby. He suggests that Mrs. Frisby seek help from the rats who live in a rosebush near her.

Mrs. Frisby discovers the rats have a literate and mechanized society. They have technology such as elevators, have tapped the electricity grid to provide lighting and heating and have acquired other human skills, such as storing food for the winter. Their leader, Nicodemus, tells Mrs. Frisby of the rats' capture by scientists working for a laboratory located at the National Institute of Mental Health (NIMH) and the subsequent experiments that the humans performed on the rats, which increased the rats' intelligence to the point of being able to read, write and operate complicated machines, as well as enhancing their longevity and strength. This increased intelligence and strength allowed them to escape from the NIMH laboratories and migrate to their present location. Jonathan Frisby and Mr. Ages were the only two survivors of a group of eight mice who had been part of the experiments at NIMH and made the rats' escape possible. Out of their respect and unending gratitude for Jonathan, the rats agree to move Mrs. Frisby's house to a location safe from the plow.

Nicodemus also tells Mrs. Frisby about "The Plan", which is to abandon their lifestyle of dependence on humans, which some rats regard as theft, for a new, independent farming colony. One rat, Jenner, disagreed vehemently with The Plan and left the colony with a group of followers at some point prior to Mrs. Frisby's arrival.

To move the Frisby home, the rats have to drug Dragon, as it is too dangerous to work in the open with the cat wandering nearby. However, Mr. Ages has a broken leg and cannot dash to Dragon's bowl to put in the drug. Since the rats are too big to fit into the hole in the wall to enter the house, Mrs. Frisby volunteers to go. Unfortunately, she is caught by the family's son, Billy, who puts her in a cage. While captured, Mrs. Frisby overhears the Fitzgibbons discussing an incident at a nearby hardware store in which a group of rats were electrocuted after seemingly attempting to steal a small motor. This has attracted the attention of a group of men who have offered to exterminate the rat colony on Fitzgibbons' land free of charge for him.

At night, the rat Justin comes to save Mrs. Frisby and manages to get her out of the cage. Mrs. Frisby warns Justin of what she learned while captured; they assume that the rats at the hardware store were all from Jenner's group and that the group of men were from NIMH and are looking for them specifically.

The successful house move allows the mouse family to remain, so that Timothy has time to recover before moving to their summer home. Although the rats have not yet had time to move everything they needed for The Plan, they manage to destroy their underground rooms and create the illusion that they are just regular rats by placing rubbish in the remaining rooms. As the others move, ten rats stay behind so the exterminators would not think the rat hole has been abandoned. When the exterminators fill the rat hole with poisonous gas, eight of the ten rats manage to escape, while two rats die in the hole. It is not revealed exactly who these two are.

Once Timothy recovers, Mrs. Frisby and her family move to their summer home and Mrs. Frisby tells her children the full story of their father and the rats of NIMH.

Related works

After his death, O'Brien's daughter, Jane Leslie Conly, wrote two other novels based on the rats of NIMH. Racso and the Rats of NIMH tells the story of a city rat who runs away to join the new colony, befriending Timothy, while saving the colony from a flood along the way. In R-T, Margaret, and the Rats of NIMH, the rats rescue two lost human children who in turn help to save the colony before winter.


In 1982, the animated film The Secret of NIMH was released, directed by Don Bluth. The film adds a mystical element completely absent from the novel, with Nicodemus portrayed as a wise, bearded old wizard with magic powers and an enchanted amulet, rather than an equal of the other rats. The character of Jenner is made a villain who is still present with the rats, rather than having left them before the story begins. The crow Jeremy has much greater prominence as comic relief in the film than he has in the book. Additionally, the Frisby family name was changed to "Brisby" to avoid trademark infringement with the Frisbee.

In production

In July 2009, Paramount Pictures set Neil Burger to write the script and Cary Granat to produce the film based on the book.

On March 4, 2015, MGM, which had released the 1982 film, acquired the rights to the book to adapt it into a live-action/animated film. Michael Berg was set to adapt it, while Daniel Bobker and Ehren Kruger would produce.

On April 10, 2019, it was announced that the Russo brothers will be executive producers of the remake.

Preceded by
Summer of the Swans
Newbery Medal recipient
Succeeded by
Julie of the Wolves
Preceded by
Mark Twain Award
Succeeded by
It's a Mile from Here to Glory
Preceded by
The Trumpet of the Swan
Joint winner of the
William Allen White Children's Book Award
with The Headless Cupid

Succeeded by
Women's History Month on Kiddle
Women Scientists of Antiquity
Mary the Jewess
kids search engine
Mrs. Frisby and the Rats of NIMH Facts for Kids. Kiddle Encyclopedia.