A Simple Theft 2: A Simple Theftier by Mark Musante

Your master Apaman has learnt about something that may help him unlock the secrets of magic, and has sent you, his apprentice, on another mission: to retrieve the sky rock from the north tower of Fossen Festning, a fortress built into the side of a mountain beside a large waterfall. All you’ve brought with you is a dark cloak and an old grappling hook that Apaman was generous enough to loan to you. All you need to bring out is the sky rock.