For nine hundred and sixty-two years the world has lived in the dark. The ninth dawn will be the last. In the frozen north, nineteen-year-old Ilyra Dask tends a dying beacon and hides a secret that could get her killed: the warmth in her hands is real. Then the lamps begin to fail across the kingdoms, a queen falls, and an order that has lit the world for a thousand years comes to claim her. With a farrier who is not what he seems, a young queen, a frost-witch, and an army of riders who never believed the old stories, Ilyra must cross a dying world to a place beneath the mountains where the truth about the sky is kept. The dawn is coming. Someone has to open the door.