Whoever Slew Auntie Roo?

Christopher and Katy Coombs are an orphaned brother and sister. Auntie Roo is a demented, sad and miserable woman who keeps the mummified remains of her daughter Katharine in a nursery room in the attic. She sings lullabies to Katharine and tries to contact her spirit with the assistance of (phony) psychic Mr. Benton. Christopher realizes that Katy is not just missing, but was kidnapped by Auntie. He and Katy place the firewood he had been fetching at the door and set it on fire with paraffin.