Sam is a nurse, and a wife, and a funny, loyal, determined friend, but it's the fact that she's Daisy's mother that's the most important thing about her. What will she do with an empty nest?

Martha has raised her son Heath as a single mum after his father left her at the altar 18 years ago. Now Heath's headed for university, and when he goes so does his child support. Martha can't imagine what her future looks like.

Alex has a successful career and a charming, gentle, wealthy husband, along with four children who couldn't be more perfect if she'd written their stories herself. Why does she keep thinking there's something else she needs?

Their friendship has survived everything they've had thrown at them since they first met at nursery drop-off. But just when they think they're managing to prepare their 18-year-olds to fledge, a cataclysmic secret from the past starts worming its way through first their children's lives, and then their own...