Frostborn: The Master Thief (Frostborn #4)

RIDMARK ARBAN is the Gray Knight, outcast and exiled from the High King's realm. Yet he alone sees the danger of the terrible Frostborn, the creatures that will sheathe the world in ice and quench all life.But none of the lords of the realm believe his warnings.  And his enemies want him dead...and the secret allies of the Frostborn wish to silence him forever. As old foes and new enemies close around him, Ridmark must fight for his life.Or else the Frostborn will return, bringing eternal ice and darkness with them.