The Family Upstairs by Lisa Jewell - 5 Stars

 When Libby turns 25 she is excited to find out what she's been waiting for her whole life: who her birth parents are. What Libby doesn't know is that she has also inherited a mansion on the banks of the Thames river in the upscale Chelsea neighborhood. The house is worth millions. What Libby doesn't know is that there are others that have been waiting on this day as well.
25 years earlier police were called to the house with reports of a baby crying. There they find a perfectly healthy, well cared for baby in a crib. There are 3 adults dead in the kitchen and 4 other children who have gone missing.

The story is told through the lives of 3 different characters in the book. It took me a few chapters to get each person straight and figure out who was who. The first half of the book is mostly back story, but at a little over half way through there was a shocking moment. From that point on, I plowed through the rest of the story and other unexpected shockers.
This is my 2nd book of the year and another 5 star rating.