Imagine, if you will, 'We Have Always Lived in the Castle' without a precocious, or particularly interesting, heroine. Daisy Fitzjohn has always lived at Brightwood, her family's estate, with her mother and, it quickly becomes clear, no one else ever. Daisy has never even left its grounds or seen another living person.
Instead, she's made friends with a rat and with a topiary and with pictures throughout the house. The house is quite large, but much of it is filled up with boxes of memories. Her mother collects the "memories" of every day and stashes them in special boxes labeled with the date. There are rules about memories and it is a ritual that must be adhered to. Only, mother hasn't returned in some time and someone new has started prowling around the outside of the house. What's a girl to do?
The treatment of mental illness was unrealistic and the whole situation absurd. I couldn't get into it, I just finished it to make sure the Rat was OK.