¡Bienvenidos a la Black Bird Academy! Black Bird Academy es una oscura escuela en la que se instruye a exorcistas cuya labor es proteger a la humanidad de los demonios. Tras ser poseída por un demonio, Leaf Young recibe una oferta dela academia: si se forma para convertirse en exorcista, recuperará su libertad.

First, there was a trunk. Inside the trunk was an egg, and inside the egg was… Well, it certainly was not a chicken. Miss Mildred Percy, former wallflower and current adventurer, is now in charge of a dragon. Along with Mr. Wiggan and Mrs. Babbinton — our stalwart companions from the first volume of Miss Percy’s adventures — she embarks on a journey across Wales, in search of the mysterious Nyth y Ddraig, or Nest of Dragons. But traveling with a young dragon in an unfamiliar land proves more difficult than anticipated. Between angry mobs, midnight rescues, and recalcitrant sheep, they battle (figuratively) their way across the countryside, defend themselves against enemies old and new, and discover something remarkable hidden in the mountains of Wales.

Miss Mildred Percy inherits a dragon. Ah, but we’ve already got ahead of ourselves… Miss Mildred Percy is a spinster. She does not dance, she has long stopped dreaming, and she certainly does not have adventures. That is, until her great uncle has the audacity to leave her an inheritance, one that includes a dragon’s egg. The egg - as eggs are wont to do - decides to hatch, and Miss Mildred Percy is suddenly thrust out of the role of “spinster and general wallflower” and into the unprecedented position of “spinster and keeper of dragons.” But England has not seen a dragon since… well, ever. And now Mildred must contend with raising a dragon (that should not exist), kindling a romance (with a humble vicar), and embarking on an adventure she never thought could be hers for the taking.