Before entering, note shiny object in ocean below. Don't forget to retrieve the magnet. Give Skeptic Spell to sheriff. Sheriff objects and locks Zanthia in adjacent cell, leaving key hanging under window. Use magnet on key.
Sheriff tosses key out of window where it gets swallowed by a fish.
Note carpet in Zanthia's cell. Click hook on window, catch fish, retrieve key. Inside City Gate. Give clerk the second Skeptic Spell. Pay three gold coins for ticket.