The Secret of NIMH is a 1982 American animated fantasy adventure film directed by Don Bluth in his directorial debut. It is an adaptation of Robert C. O’Brien’s 1971 children’s novel Mrs. Frisby and the Rats of NIMH.

Mrs. Brisby (Elizabeth Hartman), a timid widowed field mouse, lives in a cinder block with her children in a field on the Fitzgibbons’ farm. She prepares to move her family out of the field as plowing time approaches, but her son Timothy (Ian Fried) has fallen ill.

Brisby visits Mr. Ages (Arthur Malet), another mouse and friend of her late husband, Jonathan, who diagnoses Timothy with pneumonia and provides her with medicine. Mr. Ages warns her that Timothy must stay inside for at least three weeks or he will die.

On her way home she encounters Jeremy (Dom DeLuise), a clumsy but friendly crow. They both narrowly escape from the Fitzgibbons’ cat, Dragon.

The next day, Mrs. Brisby discovers that Farmer Fitzgibbons (Tom Hatten) has started plowing early. Although her neighbour Auntie Shrew (Hermione Baddeley) helps her disable his tractor, Mrs. Brisby knows she must devise another plan. Jeremy takes her to visit the Great Owl (John Carradine), who tells her to visit a group of rats that live beneath a rose bush on the farm and ask for Nicodemus (Derek Jacobi), their wise and mystical leader…