Seven old friends. One annual reunion. Countless feuds. How do friends stay friends for more than 25 years when there is so much to feel aggrieved about? Juliette and JoAnne have never got over one of them sleeping with the other's boyfriend. Sissy secretly blames someone for the death of her husband. Natasha knows one of them is having an affair with her partner. Siobhan annoys everyone. Katie is annoyed by everyone. Camilla desperately tries to keep the peace. So when their picnic in the park goes horribly wrong and one of them ends up in the Serpentine, who knows what really happened? And just what secrets from the past are about to unfold, changing everyone's lives forever?
