''The Green Knowe Chronicles'' by Lucy M. Boston is about a boy who ends up being sent to live at an old gothic manor. Strange things are afoot, however...

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* The titular children are ghosts that are trapped there. Although the children themselves are benevolent, there's a tree in the garden which the children called "Green Noah", inhabited by a demonic tree-spirit. The little poem about Green Noah is especially creepy:
-->Green Noah, demon tree,
-->Evil fingers can't catch me!
* In the fifth book, when Melanie sends a curse to Tolly's grandmother, carved on the skin of a child's hand.
** The maggots and snakes also count as this.
* The scene in the sixth book, when the Saxons are slaughtering the Britons.