There's a secret in Abernay Forest, one that allows Doctor Taur to create miraculous cures. When his talents reach the king's ears, he is called to the castle, where he meets Prince Oswin and is asked to perform an impossible procedure. As he struggles to decide what to do, the castle is attacked and the king slaughtered. The prince, now in danger, sneaks Taur out and they flee.
Meanwhile, an orphaned girl named Luna spies interlopers in Abernay Forest excavating an ancient entombed creature-the source for Taur's cures. Aware that the creature harbors a dangerous otherworlder, Luna tries to halt the excavation. But it's too late. The wraithlike otherworlder goes free...and enters Luna, taking over her body.
Fugitives Taur and Oswin must find her before she releases a deadly plague from another world.