The magic that is the heartbeat of Kosma's city is dying. Determined to fix it, she ventures outside the confines of her snow-laden tower to discover what's happening. But when her transportation spell takes her to another city entirely, one where magic is met with suspicion, she's left to rely on the closed-off and fierce Avaline for both her freedom and safe return home. Together, they make the journey North, learning unexpected truths about themselves along the way.