El Caballero de Hierro (El Hada de Hierro, 4)

For Ash, the cold Iron Prince, love was merely a mortal weakness. Until Meghan Chase, half-human and half-fairy, captured his icy heart and bound him to her with a vow to be her knight. However, Meghan is now the Iron Queen, ruler of a realm where no Winter or Summer fairy can survive. With unlikely allies, Ash searches for a way to honor his promise to stand by Meghan's side. To remain in the Iron Kingdom, he must possess a mortal soul and body. But the trials to overcome are impossible. And along the way, Ash learns that sometimes it takes more than courage to make the ultimate sacrifice.