Ghalien - A Novel of the Otherworld. Otherworld, #5

At the end of the long hallway I stepped through the broken stone and out onto the terrace behind the castle. The waterfall cascading down the steep hillside overwhelmed me with its mist, but I brushed aside its icy chill and headed for the second staircase that led into the caverns. Using touch alone, I located the dolmarehn that would take me to the foot of the Weald and stepped through. As the magic overcame me, I thought about Meghan, telling myself she was safe under Fergus's care and that soon I would see her familiar face once again.
Caedehn MacRoich was sent to the mortal world for one purpose: to hunt the Morrigan's renegade faelah. But he never anticipated stumbling upon Meghan Elam, a young woman from his own realm, nor did he expect to fall in love with her. Fate, however, had other plans for Cade and when he broke his own geis to keep Meghan safe, the Morrigan demanded retribution for his disobedience. Now, in order to guarantee Meghan's safety Cade must make a sacrifice that very well may drive him mad.
With the Celtic goddess of war playing tricks with his mind, Cade is called upon to perform another duty. The Amsihria of the north, an elusive sect of women responsible for taming Eile's powerful weather, are under attack by a horrible monster from another realm. With the help of his sister and her companions, Cade embarks on a journey that will take him beyond the edge of the Weald and further away from Meghan.
Along the way he will be forced to contend with the Morrigan's continuous assaults as well as his own doubts and fears, all the while knowing that the young woman he's grown to love remains vulnerable in the mortal world.