Katherine Armstrong planned every detail of her birthday weekend on a private island in the Everglades: the guest list, the menu, the flowers, the entertainment. She even arranged to keep the water at a safe distance.

But when a storm tears through the Glades, the power goes out, the phones die, and the island is cut off from the mainland. Then Casper, the caretaker, disappears. And in the dark water beyond the dock, something patient begins to move.

Katherine has spent years building a life that looks flawless from the outside. Now she has to hold that life together long enough to get her children off the island alive. But the longer the storm rages, the more the island reveals what it has been hiding—and what Katherine's husband may have known all along.

Because the real danger isn't just in the water. It's in the family story everyone has agreed not to tell.