Sidhe-seer MacKayla Lane has the ability to locate the Sinsar Dubh - a book with magical properties so dark that anyone who touches it will fall under its spell - but she's only interested in tracking down whoever killed her sister. Time, however, is running out as All Hallows' Eve approaches and Mac struggles to keep the Sinsar Dubh, an ancient book of dark magic that only she knows how to find, out of the hands of Fae and human alike.