They are not like other rats. They work at night, in secret...Time is running out for Mrs Frisby. She must move her family of mice before the farmer destroys their home. But her youngest son, Timothy, is too ill to survive the move. Help comes in the unexpected form of a group of mysterious, super-intelligent rats. But the rats are in danger too, and little by little Mrs Frisby discovers their extraordinary past....

Mrs. Frisby, a widowed mouse with four small children, is faced with a terrible problem. She 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. And Mrs. Frisby in turn renders them a great service....

Ellen awakens one morning with a mysterious silver frown on the pillow beside her. What magic powers it possesses she has not yet discovered, but the sudden changes in her life are unmistakable: her house is burned down, her family has disappeared, and a man in a dark uniform is stalking her. Can Ellen ever find her family? Can she use the power of the silver crown to thwart the powers of darkness? What diabolical force hides inside the mysterious castle in the woods?...

On her tenth birthday, Ellen wakes up to find a silver crown on her pillow; a few minutes later her house burns up, her parents disappear, and she is launched on an adventure involving a trek through the woods, a castle full of brainwashed captives, and the powerful Hieronymus Machine which wants her crown....