Iceling

With their scientist parents away on a research expedition, seventeen-year-old Lorna is left in charge of her younger sister Callie, an Arctic Recovery Orphan, or "iceling," who one night builds a model of an island and makes it clear that she needs to go there, and so Lorna and Callie, along with another set of iceling siblings, travel north toward the mysterious island and the truth about the icelings' origins.