If There Be Thorns - Virginia Andrews

Out of the ashes of evil Chris and Cathy made such a loving home for their splendid children... Fourteen-year-old Jory was so handsome, so gentle. And Bart had such a dazzling imagination for a nine year old. Then the lights came on in the abandoned house next door. Soon the Old Lady in Black was there, watching their home with prying eyes, guarded by her strange old butler. Soon the shrouded woman had Bart over for cookies and ice cream and asked him to call her "Grandmother."

And soon Bart's transformation began... A transformation that sprang from "the book of secrets" the gaunt old butler had given him... a transformation fed by the hint of terrible things about his mother and father... a transformation that led him into shocking acts of violence, self-destruction and perversity. And now while this little boy trembles on the edge of madness, his anguished parents, his helpless brother, an obsessed old woman and the 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....