Even though Mrs. Peregrine's Home for Peculiar Children is classified as young adult, I thoroughly enjoyed it. It's part mysterious ghost story and part coming-of-age adventure tale. Jacob is nearly 16 when his grandfather dies violently. His last cryptic words send Jacob to an island off the coast of Wales where his grandfather, as a child, had taken refuge from WWII.
Old photos, meant to be the ones Jacob's grandfather showed him, are included throughout, adding to the creepy atmosphere of the story. The clues are laid out and secrets are slowly revealed as Jacob unravels the mystery of his grandfather's youth, discovering in the process that his grandfather's grisly fate could also be his own.
There are a few violent deaths that might make this inappropriate for younger children, but the gore isn't excessive. It should be fine for junior high and up.