If there be thorns - Virginia Andrews

Out of the ashes of evil, Chris and Cathy have made a loving home for their children. Fourteen-year-old Jory is handsome and gentle, and nine-year-old Bart has a dazzling imagination. Then the lights come on in the abandoned house next door. The old lady in black is there, watching their home with prying eyes, guarded by her strange old butler. Soon she has Bart over for cookies and ice-cream, and asks him to call her 'Grandmother'. And Bart's dark transformation begins... While the little boy trembles on the edge of madness, his anguished parents, his helpless brother, an obsessed old woman and her vengeful, powerful butler await the climax to a horror that flowered in an attic long ago - a horror whose thorns are still wet with blood, still tipped with fire...