With the discovery of Mr. Willoughby's diary in this third book of the Martina MacKenzie series, the trio sets off on yet another wild adventure in Sheardland. To find the missing earth key, Martina, Heath, and London disguise themselves as Elfin servants at Womeldorff Castle. As they piece together clues, they struggle to continue Mr. Willoughby's work without getting caught in the inferno.