From the Kickstarter campaign page:
Adventure: This tabletop role-playing game adventure also is a self-contained mini-setting. Because the action takes place on a flying circus, Dreams of Aerie is easy to adapt to any game world. Drawing on Barnum & Bailey and Cirque du Freak, this book's main plot elements involve a murder mystery, the rivalries of circus guilds, urban adventuring, and monster-hunting. Countless hooks allow side trips and alternate storylines, as each of the 90+ circus folk hide shadowy pasts and secret motivations. The heroes must contend with secret societies vying for hegemony among circus folk. If left to its own devices, a monstrous presence hidden aboard heralds catastrophic world events.
Sourcebook: This book's setting includes the circus itself, standing amid side shows and carnie shacks, themselves surrounded by a ring of permanent shops and dwellings called aeries, perched at the edge of the clouds. Two more decks lie below with all that the Greatest Show on Calidar needs to function, as well as its dark secrets. Although written for the World of Calidar, this setting is nearly self-contained until the referee starts unfolding the hidden stories of circus folk, and connects them with the chosen game's universe.
Contents: Dreams of Aerie is a 124-pg full color book, 8" 3/4 x 11" 1/4, which may gain additional pages and internal art as stretch goals are reached. Deck maps are included in the book, as two-page spreads, along with inset maps. Deck maps can also be obtained as separate 12"x18" posters, labeled or unlabeled, depending on one's pledge or as add-ons. This book is system-neutral: guidelines to help adapt the adventure's game statistics to common RPGs are bundled with the book at no charge. This digital file and a series of game aids for the players and the referees can be printed for quick reference during play.