The Scream (PB) by Joan Aiken
David's gran scares people.
Her neighbours whisper that she possesses the power of the Evil Eye. She is strangely fascinated by The Scream - a painting of a person overcome by terror. When she moves to live with David and his sister, her presence seemst o spark a series of sinister and tragic events. And the evil forces that have been unleashed can only be stopped by a dangerous journey to the mysterious island where Gran was born.
'As thrilling and unsettling as you'd exect from this author.' Observer
'A tense, strangely disturbing story' The Parent's Guide