Edge of Mercy — C.C. Marks

Charlie hides her true identity, but her very presence places everyone around her in danger. With no other choice but to remain where she is, she stays with a community that might not be as benevolent as it appears. In this new and dangerous version of the world, where a friend might be an enemy and an enemy might be a friend, seventeen-year-old Charlie protects her baby sister and herself from grotesque monsters outside the community as well as human ones inside. Will the truth she discovers about her protectors save her or ultimately doom her to a fate worse than death?