The Unicorn's Tale Nathaniel Fludd, Beastologist Series, Book 4.

Is there no rest for the travel worn and weary? Not if you're Nathaniel Fludd, the world's youngest beastologist-in-training! All Nate really wants is to track down his missing parents, but when a unicorn falls mysteriously ill, Nate's Aunt Phil makes it clear where a beastologist's duty lies: to the beasts. And if taking care of the world's beasts isn't difficult enough, Nate and Aunt Phil must also keep them safe from the villainous Obediah Fl...