Saint Philomene's Infirmary for Magical Creatures

In W. Stone Cotter's Second Chance, the young readers fantasy sequel to Saint Philomene's Infirmary for Magical Creatures, a brother and sister duo return to a magical underground realm to prevent disaster.
Chance and Pauline Jeopard have been on an incredible adventure—one they can never talk about. After all, who would believe that a magical realm exists deep below ground, home to extraordinary creatures found only in fables? Worse yet, what if someone did believe?
When a miner finds out about Donbaloh and threatens to drill and destroy it, Chance and Pauline must travel back to warn its inhabitants—risking it all in the process.