Severed Ties (jagged Scars) (volume 2)

Wendy is no stranger to death--she killed her first Skinny before she was ten--but the slaughter of her family is personal. Pelton's betrayal to the Den planted a wicked seed in Wendy's heart that is slowly growing into a ravenous monster bent on revenge. Its rage is bleeding into her dreams, her nightmares and her waking hours, staining everything, including her sanity. When the monster almost overpowers her, Wendy decides she should leave Shelter. But before her friends will let her go, a plague sweeps through the complex. Doc doesn't have the meds they need to cure it, but the map Wendy wrestled from Pelton could lead them to a place that does. Now Wendy must hold her mind together long enough to keep everyone she knows from dying. Again