This is a fairly typical plot for this sort of adult-chick-lit: middle-aged parents, adult children each with his/her own problems, and an aging Gran thrown in. Also a pitiful little dog. All very relevant, especially as the background is the current economic crisis. But Buchan keeps sending mixed signals. Tom and his wife Annie, who have slept in separate bedrooms for years [since their elder daughter left home, for which Annie blames Tom, it turns out] are forced back into one room when Tom's 80+year-old mother's investments will no longer sustain her in a care home and she comes to live with them. The proximity has Annie and Tom each reacting to the other's physical presence in ways that seem tender and at least semi-erotic. So you keep thinking: Will they? Have they? When will they? and all the time Annie is talking to her best friend at work about leaving Tom. So there is no clear through line here -- and maybe that's realism, but for the reader it's confusion.
One of the best things about the book is the grandmother, not that she is likable. Everyone is kind to her, heroically so, considering how much they didn't want her there. She articulates her feelings about being alone and suffering loss of everything that made life valuable to her, and points out that soon Annie, whom she has never liked, will one day be in her situation.
The book ends abruptly, with the implication that this one turn of the cards is going to make everything all right again. I think Buchan just got tired of all these fairly dull people.