Thank you NetGalley for this advanced copy. I was thinking based on the description that a little girl went missing; not an adult. But this book overall was very mediocre to me. I ended up reading the beginning, then skipping to the middle to see what was going on, then skipping to the back to see the ending. Didn't hold my attention that well.

The Favorite Child by Cathryn Grant
Annie’s sister has gone missing. Why doesn’t anyone care?
Annie feels like she's at a good place in her life. Happily married, expecting her first child, enjoying a vacation with her extended family at their beautiful summer home.
But then her sister, Sunday, suddenly goes missing.
Annie is immediately concerned, but the rest of the family assure her that everything's fine, this is the kind of thing Sunday does, she'll be back…
But Annie knows in her heart that something is very wrong. And she won't rest until she sees her sister safe and well.
As Annie digs for the truth, she realises that some of her family are not what they seem. And as she draws closer to uncovering their horrifying secret, Annie finally understands that she and her unborn child are in terrible danger…
A really enjoyable read. Twisty. I liked Annie. How she wouldn't give up. Recommend. 4*.