The novel is about a 16 year old girl named Mercy who is training to be the next shaman for her secluded treetop village on the night that blood rains from the sky. During the storm, the enemies of her people, the bat-like beast-men called "Blood Wings" are incited into a blood frenzy during an attack that nearly destroys her tribe. The village chieftain sends her on a mission of honor to find the source of the rain, forcing her to flee the village in the midst of the battle. Her mission takes her from one corner of the continent to the next and Mercy is forced to befriend potential enemies, spies, and even one of the Blood Wings to uncover the truth about the blood rain. As Mercy searches for answers she uncovers secrets from her past, lies that are widely accepted as truths, and a terrifying secret hidden by the beast men themselves. Everything points to a powerful magic which disappeared hundreds of years ago. If magic resurfaces in the world everything will change forever.

Emily is a young woman struggling to earn respect as a mechanic in London after she inherits her Father’s business.  When her childhood friend and lover, Victor, returns to England, things finally seem to be improving for her, until he fixes her Father’s watch and they discover the mysterious blueprints inside along with a cryptic note warning her to hide the blueprints and to avoid “The Guildsmen.”  Emily becomes entangled in warring secret societies, corporate espionage, and old rivalries in an attempt to save Victor’s life and uncover the truth about her Father’s death.

The main character, Orel, is different than everyone else in his hometown.  He is faster, his eyes are a strange color, and he has a unique ability that no one else in his town possesses, the ability to summon spirits.  He single handedly has turned the once depleted mine into a prosperous coal town.  Still, his life changes when a shrewd railroad baron, Everest Wildworth, buys the town and blackmails Orel into working for him.  Orel moves to the city where the spirits he summons are used to aid in the creation of a new type of fuel.  While there, Orel learns about his heritage.  He’s descended from a strange tribe of creatures called the Aves and he’s having trouble coping with who he really is and where he really came from.  Still, despite everything else, he knows what he really needs to discover is why the spirits are disappearing and what Wildworth is hiding.