The Wrong Mother by Sophie Hannah

Flap copy from paperback:
"Sally Thorning is watching the news with her her husband when she hears a name she never thought she'd hear again: Mark Bretherick. It's a name she shouldn't recognize. Last year, a work trip Sally had planned was canceled at the last minute. Desperate for a break from juggling her job and a young family, Sally didn't tell her husband that the trip had fallen through. Instead, she treated herself to a secret vacation in a remote hotel. While she was there, Sally met a man- Mark Bretherick.

All the details are the same: where he lives, his job, his wife Geraldine and daughter Lucy. Except that the photograph on the news is of a man Sally has never seen before. And Geraldine and Lucy Bretherick are both dead..."

This dark thriller starts out with a bang, quite literally, and keeps ratcheting up the suspense until the shocking end. Sally Thorning's life takes a turn toward the surreal when she discovers the man with whom she shared a weeklong affair is not in fact the man she thought he was. As she attempts to unravel that mystery, police are investigating the apparent murder-suicide of that man's wife and daughter. As the book alternates between Sally's deteriorating situation and the police investigation, the suspense and questions build toward a stunning crescendo.

This book kept me guessing until the very end, and left me eerily staring over my shoulder on the street. The story is quietly dark and I was impressed by the thrills the author achieved in this psychological drama. The writing was tight and the voice never faltered though it was sometimes hard to understand Sally's actions in light of developing events. The Wrong Mother was my first exposure to Sophie Hannah- I'm delighted to discover she has other books I can add to my wishlist. Highly recommended psychological thriller.