They keep each other's secrets. They hide each other's lies. They were destined to be best friends. The four girls - all born that same hot summer. There was even a newspaper article after they were born. They said there must be something in the water on Larkspur Close. They predicted a safe and happy life for them all. . . More than thirty years later, it's more than an unbreakable friendship - it's more like a sisterhood. It's the girls who Jess reaches out to because she's worried about her grandparents who've raised her since her mother disappeared, who Erin tells about her new business idea, who Melissa calls to say she's desperate to escape her toxic job. But then Chantelle messages saying she's discovered her husband is having an affair. And everything changes. Because then her husband is found dead. . . And only a few people knew about his secret. Is it just a terrible accident? Or will someone stop at nothing to keep the girls of Larkspur Close safe and happy?