The Ghostfaces

A storm drives the Heron across the ocean and into a bay no map has ever shown them. The coast is unfamiliar, the people speak no language the Herons know, and the village is bracing for the return of a raiding tribe — the Ghostfaces — that takes slaves and kills anyone who fights back.

The Ghostfaces is the most standalone of the later Brotherband books and the one that most visibly borrows from a real historical source — the Skraeling-era encounters between Norse sailors and the peoples of eastern North America. The Herons stay the winter and help a people they will, by the end of the book, never see again.