Daisy Darker was born with a broken heart. Now, after years of avoiding each other, Daisy Darker’s entire family is assembling for Nana’s 80th birthday party in her crumbling gothic house on a tiny tidal island. The family arrives, each of them harboring secrets. When the tide comes in, they will be cut off from the rest of the world for eight hours. But at the stroke of midnight, as a storm rages, Nana is found dead. And an hour later, the next family member follows. Trapped on an island where someone is killing them one by one, the Darkers must reckon with their present mystery as well as their past secrets, before the tide goes out and all is revealed.