From the books description:
A Shadow Man is stalking the children of Ard, leaving the dead lying in the forest with their eyes black pits. The people are in a panic, but the investigating Ruad philosophers have no explanation. Seeking someone to blame, the people of the ancient city of Ard demand the head of the most dangerous person in their midst, the giant Waylaid.
Once great among the Fomor—a prince, a sorcerer, a priest, Waylaid has been cast out by his people. He has come to Ard with his Bolg apprentice, Piju, to live quietly and study in Brea’s library. Can he escape the maddened crowed and find the killer without breaking his vow to give up sorcery?
And has he failed to teach his young and impetuous apprentice the most important lesson of them all, that the price of using sorcery is always too high?