Seven days. Three families. One killer.It was supposed to be the perfect holiday - a group of families enjoying a week together in the sun. Four women who have been best friends for as long as they can remember - Kate, Rowan, Jennifer and Izzy - making the most of a luxurious villa in the south of France.But Kate has a secret: her husband is having an affair. And a week away might just be the perfect opportunity to get the proof she needs - to catch him in the act once and for all. Because she suspects the other woman is one of her two best friends.One of them is working against her, willing to sacrifice years of friendship to destroy her family. But which one? As Kate closes in on the truth in the stifling Mediterranean heat, she realises too late that the stakes are far higher than she ever imagined . . .