I have to declare this book a sleeper. The first 100 pages or so are bland, but when the plot twist kicks in, it grabs you by the throat. A young couple buys an old house, and they make a grisly discovery, blah, blah. But then, they start to suspect the in-laws, who live close by. There are obvious complications because of their relationship, but the deeper they dig, the more they discover, and it snowballs from there.
Warning. There are pretty realistic depictions of children being killed. Just tell yourself it’s just a book. This could be upsetting, but if you can compartmentalize it, it’s worth reading.