Good, good, good book, and why I have seen it categorized as a romance novel is beyond me. I mean it's no Hunt for Red October, there are relationships in it, some of which are romantic. But romance itself is most certainly not the focus.
The story centers on three seemingly unrelated women, whose stories eventually intertwine due to the secret of the title. Which husband had the secret and what the secret was is revealed fairly early, but still I couldn't stop turning the pages. I have been looking for a book like this, and I'm glad I got past the "romance" nonsense and read it.