This is a hard book to review because it'd be so easy to spoil it and I don't want to do that. I also don't want to hide most of my review behind spoiler tags so...The book mostly centres around two couples. David and Dawn are a writer and his teacher wife who go into New York for the lunch that seals his first book deal. It's a big day for them but on the way home David accidentally bumps into someone in the street. Someone who then follows him to the station and asks him to "Remember me".The other couple are John and Kristina. A waiter and bar-maid at an Italian restaurant who've been together about 6 months and are at the stage where they are about to either get more committed or possibly split up. Kristina's new friend from her book club has seemingly acquired a stalker and asks John and Kris for help.Both these stories concern people who live in a kind of parallel world. They are there in the background of our lives but often go unseen or unnoticed. But something is changing. They are coming out of the shadows...I could talk more - vaguely and circuitously so as not to spoil - about the plot but I won't. Let me talk instead about tone and themes. This is a book about regret, about loss of friendship and the way we forget people. It's also about what it means to really live in a place and be part of someone's life. In that sense it deals with some universal and weighty themes and does so well I think. However it's not a ponderous literary novel. It's a thriller. It reminded me of Stephen King in places, which is a compliment. I enjoyed several of the characters. The author writes a middle-aged lady with nine cats who lives in a trailer - and he manages to make me really like her :)It's not perfect. I think it could have been shorter. Particularly in the middle section where dramatic irony is stretched to the breaking point. Also, I was going to complain that there was an un-fired Chekov's Gun in the form of very significant events from one character's past which are mentioned more or less in passing but never really dealt with. However it turns out that this character, and these events, are from a previous book. Also they are mentioned because they affect who this person sees and interprets events in this story, so the gun is fired - it just has a quieter bang than you might think.Anyway it all comes together in the final part of the book and we get a dramatic action-y ending. It left me feeling I'd enjoyed the ride.