The Influence by Ramsey Campbell
Trade paperback format.
Now a major Netflix movie.
"This is a chilling work and the fullest treatment of one of Campbell's recurring themes - the psychic violence family members wreak upon one another." Publishers Weekly
Queenie is the ageing matriarch of the Faraday family, and even death can’t break her hold over her eleven-year-old granddaughter Rowan. She’s buried with a locket that contains a lock of Rowan’s hair, and soon afterwards Rowan is befriended by a mysterious uncannily intelligent girl of her own age. Only her aunt Hermione suspects how sinister this is, but will retrieving the locket save her niece? By the time anyone sees what effect the ghostly influence on Rowan is having, it may be too late for her. if the child who takes her place in the family isn’t Rowan, Rowan may be somewhere else not quite like our world…