A compelling domestic-suspense novel full of twists and turns

The Wife Between Us is a compelling domestic-suspense novel full of twists and turns. While I did enjoy it and had a tough time putting it down, I appear to be in the minority. The story is told in three parts. Part one was great but somewhere along the way my attention began to wane. I suppose some areas were a bit too slow for my liking. I did however, enjoy the writing style and I like that it's not obvious that there are two authors.

I'm not going to get into the plot as with most thrillers you're better off going in blind but as I said, this book is full of twists - the first and last being the best.
I have An Anonymous Girl sitting on my shelves so I'm looking forward to reading that soon.