The Secret of NIMH
Don Bluth · 1982
A widowed field mouse named Mrs. Brisby has to move her sick son before the farmer's plough destroys their home, and finds help among a colony of unusually intelligent rats who escaped a laboratory years earlier. Don Bluth directed the film as his debut after leaving Disney's animation department with several colleagues in 1979 to found an independent studio, taking on a book Disney had rejected twice before, adding mystical elements not present in the source novel, and finishing the whole project on a tighter budget and schedule than the studio he'd left would have allowed.