Seven years ago, the Keld took Tobin Callow's father. Now it has taken a six-year-old girl-and this time Tobin can go after her.Posy Tarrant leaves her clothes neatly folded beside the river and walks willingly into the water. Tobin knows the old promise protecting his family does not protect her, so he follows her beneath the Keld into the River Kingdom and brings her home.Cold. Hungry. Frightened. Alive.Then Posy begins to heal people.Fevers break. Wounds close. Old pain disappears. Word spreads, and strangers begin arriving in the valley to seek the child the river gave back. A House of Living Water grows around her. For people who have spent years suffering, the miracle is real-and refusing it starts to look cruel.But the healed are changing. Memories fade. Fear disappears. Pale cords appear around their wrists. And beneath the Keld, something that had been dying is growing stronger.As a new weir alters the river's flow and an old bargain begins to fail, Tobin must uncover what the River Kingdom truly wanted from Posy before an entire community willingly gives the water more than it understands.WHAT THE RIVER CANNOT TAKE is the concluding volume of THE RIVER KINGDOM, a complete two-book supernatural folk-horror story about family, grief, dangerous mercy, and the price of relief.