The Sister by Poppy Adams

The present-day part of this book takes place from a Friday to a Tuesday. Ginny(age 70) has lived alone in her family's deteriorating mansion for decades - since the death of her mother and the departure of her father. As a young girl, Ginny worked with her father on experiments with moths. She worked on the research for years and was successful. But it wasn't a job that often took her away from the mansion and she gets weirder and weirder as the years pass. Now, out of the blue, her younger (everything is relative!) sister Vivien has written that she is coming to live with Ginnie. Since she has had no contact with her sister for 30+ years and since she likes doing things her own way, Ginnie is not very happy! During the narrative of these five days there are lots of conversations and flashbacks to fill in the story of the past 70 years. It's sort of eerie. There are, of course, the usual family secrets, etc. Author Harlan Coben called this book "lyrical and haunting" - wish I would have thought of that.