Icefall — Matthew J. Kirby

Trapped in a hidden fortress tucked between towering mountains and a frozen sea, Solveig, along with her brother the crown prince, their older sister, and an army of restless warriors, anxiously awaits news of her father's victory at battle. But as winter stretches on, and the unending ice refuses to break, terrible acts of treachery soon make it clear that a traitor lurks in their midst. A malevolent air begins to seep through the fortress walls, and a smothering claustrophobia slowly turns these prisoners of winter against one another.

Those charged with protecting the king's children are all suspect, and the siblings must choose their allies wisely. But who can be trusted so far from their father's watchful eye? Can Solveig and her siblings survive the long winter months and expose the traitor before he succeeds in destroying a kingdom?