Cinnia is a half-dakini. Born from a human mother and a dakini father she has the ability to change form at will. Together with the rest of her kind she has lived among humans for her whole life, never revealing their true identity. But when humans are starting to kill half-dakini all over the world, Cinnia has to find out what is going on. 

*Okay, so this idea came to me in a dream (I know it sounds cliché, but it did) and I thought it sounded like something which might work:)

PS. A Dakini is a demon-like creature (therefore also regarded as such on Earth)