Deyla told you that books and advanced crafting techniques concerning Aether had recently been stolen. She explained that information about Aether had to be kept secure, as it could empower the enemies of Asmodae. You went to the Airship Dock to get information and then followed the trail to traders Berth in Altgard. You heard that the man in black robe had already left for Impetusium. Finally, you were able to dispatch the Mau spy who had disguised himself as a Human, and retrieve the books from near the Black Claw Village.