Six years ago, little Katherine Harlow killed her parents. Showing no signs of regret or remorse, she was said to be a girl without a soul: A Hollow Girl. Now, wearing an expressionless white mask, Kat kills for the dead, a willing vessel for the souls of the wrongfully killed. But how did a disturbed little girl become a brutal vigilante? And are the voices she hears really those of the dead, or symptoms of a dangerous, all-consuming psychosis.