Mrs. Murray’s Ghost (The Piccadilly Street Series Book 1) by Emily -Jane Hills Orford

It’s 1967 and Mary’s family has moved into a huge Victorian mansion. She loves her gigantic new house, especially her room. But then she begins to meet the house’s other residents. Mrs. Murray was murdered in Mary’s new house. At first she tries to scare the new residents away, but there seems to be a force connecting the ghost to Mary. Even the stranded Brownies, the little people who live between the walls, feel that connection. When Mary becomes deathly ill, the Brownies and the ghost team up to try to rescue…