Heir to Sevenwaters — Juliet Marillier

The chieftains of Sevenwaters have long been custodians of a vast and mysterious forest, one of the last refuges of the Tuatha De Danann, the Fair Folk. Human and Otherworld dwellers have existed there side by side, separated by a thin veil between the realms and sharing a wary trust.

Until Lady Aisling gives birth to a son-a new heir to Sevenwatersand everything changes. With Lord Sean facing his own difficulties as waning factions threaten his borders, it falls to their daughter, Clodagh, to care for the infant while her mother recovers.

Then the baby is taken from his room and something unnatural is left in his place. To reclaim her brother, Clodagh must enter the shadowy Otherworld and confront the powerful prince who rules there. Accompanied on her quest by a warrior who may prove to be more than he seems, Clodagh will have her courage tested to the breaking point. But the reward may be far greater than,she ever dreamed....