Hen and her husband Lloyd have settled into a quiet life in a new house outside of Boston, Massachusetts. Hen (short for Henrietta) is an illustrator and works out of a studio nearby, and has found the right meds to control her bipolar disorder. Finally, she’s found some stability and peace.

But when they meet the neighbors next door, that calm begins to erode as she spots a familiar object displayed on the husband’s office shelf. The sports trophy looks exactly like one that went missing from the home of a young man who was killed two years ago. Hen knows because she’s long had a fascination with this unsolved murder—an obsession she doesn’t talk about anymore, but can’t fully shake either.

Could her neighbor, Matthew, be a killer? Or is this the beginning of another psychotic episode like the one she suffered back in college, when she became so consumed with proving a fellow student guilty that she ended up hurting a classmate?

The more Hen observes Matthew, the more she suspects he’s planning something truly terrifying. Yet no one will believe her. Then one night, when she comes face to face with Matthew in a dark parking lot, she realizes that he knows she’s been watching him, that she’s really on to him. And that this is the beginning of a horrifying nightmare she may not live to escape. . .

Now that I’ve read Before She Knew Him, all I want to do is talk about it. Only I can’t. Not because there isn’t anything to say (there’s plenty.) And not because the book is bad (it’s so good.) I can’t talk about it because I don’t want to risk giving away a single one of its many surprises.

Here’s what I can tell you: When Hen—short for Henrietta—and her husband, Lloyd, move into a new house, they quickly meet Matthew and Mira, the only other childless couple in the neighborhood. While having dinner at the neighbors’ house, Hen lays eyes on a peculiar object that ties Matthew to an unsolved murder from years before. Is Hen’s neighbor a killer? Or is her bipolar disorder, something she’s struggled with in the past, returning to mess with her fragile mind once more?

Sounds like a book with an ending you can see coming after turning the first page. It’s not. At all. Before She Knew Him is deeper, darker, and more twisted than it seems. Once you read it, you’ll know exactly what I’m talking about. And why I absolutely can’t tell you any more right now.