The Changeling Warriors

Peter, a thirteen-year-old loner, is forced by his mother in England to spend two weeks of holiday with his recently widowed aunt on the Irish island of Inishbofin, or the Island of the White Cow. On the ferry across, he meets Siobhan. She's a year older. The island is suddenly struck by two tragedies, as two islanders have gone missing. On a walk, Peter meets two small men, who turn out to be the Irish fairy leprechauns.