Heir to Sevenwaters: Sevenwaters, Book 4 (Unabridged‪)‬

The chieftains of Sevenwaters have long been custodians of a vast and mysterious forest and a new heir has been born. But the family's joy turns to despair when the baby is taken, and something unnatural is left in his place. To reclaim her newborn brother, Clodagh must enter the shadowy Otherworld and confront the powerful prince who rules there.