Young Eily lives on the Irish coast near the enchanted isle of Lisnashee where the Good People, or fairy folk, dwell. The villagers are careful to stay far away from the island, fearing the consequences of angering the sinister sprites, who have been known to spoil livestock, wreck ships, and steal people away in the night. Despite the danger, Eily's family members have visited the island for many generations. As fog catchers, they must journey to Lisnashee once a year to gather magical beads of mist that will help grow herbs the local apothecary uses for protection charms, potions, and healing ointments. Fierce winds and dark skies herald a treacherous crossing to Lisnashee for Eily's father this year. When she discovers his protection charm bracelet, accidentally left behind, she makes the perilous sea voyage to rescue him.