In this outing, a young-appearing woman got a coin -- less toxic than the coins in Jim Butcher, but the same general idea: what do you want i'll give it to you type of thing. She did not know that her other mother had already used it. Chloe uses it to turn herself into an energy vampire, only she sort of missed a couple possible consequences. Also, she's a vegan.
She's been living this half-starved life for two plus decades when a guy who claims to be a Federal agent but appears to be operating on a shoestring budget enters her life and asks her to investigate Dr. Katterfelto (one of the overlapping characters, IIRC). Antics ensue.
It's a lot of fun, and includes a whole roller derby team, as well as having part of the magical energy problem being resolved in a way that reflects my ideas about attachment. I may go back and reread the series; there's supposed to be another one out later this year.