True evil is a persistent and tenacious beast. Its desire for existence is eternal and insatiable. It needs to infect only one mind for its insidious philosophy to take root and spread. It is 394 B.C. At a remote loch in the highlands of Northern Albu, a priest sacrifices nine innocents. Below the water’s surface, a shape feeds on their blood and begins to take form. Soon it becomes sentient and begins to hunt. Sidheag has risen. Humans cannot defeat the abomination. Neither can Mongfhionn, the powerful leader of the Aes Sidhe. The only remedy is the Blood Queen and Gràinne is the sole heir to that throne. Will the Blood Queen stand alongside Mongfhionn to confront Sidheag? Yet the cost for Gràinne may be too much—unless her daughter, Brianag, is in jeopardy.