Phonogram: The Immaterial Girl #3

Plot

Music is magic, Emily Aster sold half her personality for power to the King Behind The Screen. Nearly a decade later, ruling a Coven of phonomancers, she has momentary doubts that she did the right thing. Her discarded half takes the opportunity to swap places. Now Claire takes over Emily's life ... and Emily is trapped in a world of music videos. But traveling through a certain video, she may have found a way to escape...