Poppy and Callihan have both made mistakes in their marriage, but are still deeply in love. The revelations they make to each other (and us the reader) reveal lies & vulnerabilities that need to be exposed before they can move forward in their relationship. Callihan's plotting is fantastic. There are points in this book where I'm not sure how the characters are ever going to get out of the situation they've landed in, yet they manage to pull through.
I'm definitely going to be reading the next book.