Cold bites at my nose and cheeks. Despite the fact that I’m wrapped head to toe in thick wool outerwear, I’m shivering as I stand on deck, watching as we approach the rugged black island that Mossie calls home. It’s no wonder that no one bothers the Selkies at their home base.

The island towers over the sea, its tall cliffs made of black obsidian that shines in the moonlight. No trees interrupt its landscape. No other land is visible on any horizon. It stands alone, ...