This is an extremely clever, brilliantly written, creepy little psychological suspense/horror. The author seems to love the same horror movies and novels as me, because the book is chock-full of references to them, especially The Exorcist, and I had great fun spotting them all.
A Head Full of Ghosts is about eight year old Merry and her older sister Marjorie, who is fourteen. Despite the age gap the sisters have a close, loving relationship, until Marjorie starts to behave strangely. Is she having a psychotic breakdown, or has she been possessed by a demon? Or is she just faking the whole thing? When the medical profession are unable to help, her parents call in the local catholic priest. It's then that events spiral out of control and the family find themselves starring in a TV reality show called The Possession.
The narrator is Merry, both as an eight year old and then, fifteen years later, telling her story to a journalist writing a book about the events. It took me a while to grasp that the 'fifteen years ago' is actually the present and the adult Merry is telling her story from fifteen years in the future. I was pulled out of the story a few times with the references to smart phones, thinking 'I'm sure smart phones weren't invented fifteen years ago' before I worked it out. Merry's narrative is also interrupted by extracts from a horror fan's blog, written in a very bouncy style, which I actually really liked - it was a nice contrast to the bleak bits!
Anyway, I absolutely loved this book and I now have a new favourite author. I would recommend it to fans of psychological suspense, and authors such as Henry James (Turn of the Screw) and Shirley Jackson (We Have Always Lived at the Castle). However, anyone looking for a traditional horror story might find the shocks are a bit spaced out. Be aware that the story is bleak in places - and watch out for a twist so subtle you might miss it. And that the last 10% of the book is comprised of additional material, including the author's notes (fascinating!), and questions for book clubs, so it's shorter than it appears.