Uppsala, Sweden, 1842. Luna is a fossegrim, a violin-playing water spirit who will teach her arts to mortal musicians, for a price. But with belief in the fair folk dying, their wisdom, too, is in danger of disappearing from the world of mankind. Yet one night, Luna finds hope in a small boy, a boy who could pass for a fairy child, but he is not-he is human.

A crossover with "The Man Who Laughs" by Victor Hugo. After saving a fellow disfigured soul from drowning, Erik finds himself ensnared in a conflict which threatens to tear his new-found friend from his true love, a blind girl.