Tam Lin - Faerie Tales, #1

After a fall out with his fiancé, Tom Lane needs a change of pace--more accurately, an escape so he can lick his wounds. He travels to Ireland in search of his Ulster-Scots roots. There, Tom has an eerie sense of being watched. He's almost ready to leave, until he meets Fergus and Aoife, married tour guides. The couple offer to show Tom a little more than the sights. He's having the time of his life.
However, little things aren't sitting right with him about the couple or the Irish castles he's touring. It's almost as if he can see something else. Another world superimposed on his own. Has Tom found the ultimate escape, or has he fallen for the same trap the fae have laid for centuries?