A mysterious illness has been spreading throughout the fey and once again Morgan Lafayette is called to action. She returns to act in her role as Chosen, but this time she is missing her faithful sidekick Tilson. With the danger ever rising, the haltija has chosen to leave her side.

In her search for both a cure for her friends and to stop the illness from spreading, Morgan has to travel even further than she had ever expected in order to find a cure and save her friends. From the bottom of the ocean to a magical land far above the treetops, Morgan faces more danger - and more excitement - than ever before.

As she hunts for the cure, she uncovers information about those she thought she knew, leading her to wonder which of her friends were true and how far the fey could be trusted... if any of them could be trusted at all.