Hollow Girl: Little Sister (Hollow Girl #6)

There's a girl in a mask killing bad guys, but it's not Katherine Harlow. She's disappeared and a less experienced but enthusiastic wannabe has sidled in to take her place. You can bet that when Kat returns to reclaim Hollow Girl's mask, there's going to be a reckoning, and not just with her 'Little Sister'. Because Detective Collins has crossed a line, leading to an inevitable and bloody final showdown.