W. Stone Cotter chooses as the setting for his middle-grade adventure novels the vast, hidden caverns that yawn within the Earth’s crust, territory largely held by fantastical creatures that seldom, if ever, intersect with humankind. In Saint Philomene’s Infirmary for Magical Creatures and its sequel, Second Chance, we discover exactly what happens when humans (two siblings, in fact, ages twelve and fourteen) find their way down below.