From the introduction:
The adventure begins in the sky over Old Venice, while the characters are flying to (or from) the Teutonic Federate Principalities. They are traveling on an astonishing aircraft built in Ferrara and their mission could be diplomatic, or linked to another adventure or campaign. I.e. the aircraft might be directed to Lucca for the upcoming Universal Council (see the official campaign Once upon a time in Lucca) or the reason of the travel is somehow connected with The secret of Marco Polo, the four-parts adventure you can find in Ultima Forsan: Setting Book. The sly Hilaire von Aschenbach and her Lazzarettos are an encounter in common for both adventures and you can manage their mood and reaction according to previous encounters.
Suddenly a cannon hits the flying ship.