Principles of Angels (Hidden Empire, Book 1)

Khesh City floats above the surface of the uninhabitable planet of Vellern. Topside, it's extravagant, opulent, luxurious; the Undertow is dark, twisted and dangerous. A place where nothing is forbidden, Khesh City is also a democracy, of sorts, policed by the Angels—elite, state-sponsored killers who answer only to their enigmatic master, the Minister. Taro lived a privileged life with his Angel aunt until a strange man, who bought his body for the night, followed him home and murdered her. Taro wants to find the killer who ruined his future, but he's struggling just to survive in the brutal Undertow—then an encounter with the Minister sets him on a new course. Elarn Reen is a famous musician sent to Khesh City as the unwilling agent of mankind's oldest enemy, the Sidhe. To save her own life, she must find and kill a renegade Sidhe. As Taro and Elarn's paths converge, it becomes clear that the lives of everyone in Khesh City are at risk—and a common prostitute and an uncommon singer are the city's only chance.