Icefall by Matthew J. Kirby (author) (US edition)

Like Game of Thrones for YA readers. Traitors and dark evil close in on the king’s children, trapped in their hidden fort by winter ice. Utterly chilling. Caught between towering mountains and a frozen sea is a remote castle. Inside is Solveig, the king’s daughter; her brother, the crown prince; their older sister and an army of restless warriors. All of them anxiously await news of the king’s victory at battle. Soon, he will arrive to set them free. But as winter stretches on and the ice refuses to break, grisly acts of treachery show that a traitor lurks in their midst. A malevolent claustrophobia seeps through the fortress, turning these prisoners of winter against one another. Who can be trusted? Will Solveig and her siblings survive the long winter?