The Demon Girl, by Penelope Fletcher, is free in the UK store only (it is available to US and UK customers in the US store, but is $0.99 or £1.33, respectively). It's also free on Smashwords, for all countries and in multiple, DRM-free formats.
Book Description
Rae Wilder has problems. Plunged into a world of dark magic, fierce creatures and ritual sacrifice, she is charged with a guarding a magical amulet. Rae finds herself beaten up, repeatedly, and forced to make a choice: to live and die human, or embrace her birth-right and wield magics that could turn her into something wicked, a force of nature nothing can control.
Click HERE to get the book free from Smashwords.