Dark Highlander ~ Karen Marie Moning

This is the fifth book in the Highlander series. Deagus McKelter broke the compact with the fearie, he used the standing stones to go back in time and save his brother's life, and now the spirits of thirteen evil druids are trying to take him over. One day Chloe Zanders walks into his New York penthouse to deliver an ancient text to him, and he knows he can never let her go, but also can not offer her a future unless he figures out how to rid himself of the evil druids.